JP2006291284A - Partial plating method and method for manufacturing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To partially form an electroless-plated film superior in adhesiveness on the surface of an inorganic oxide with high accuracy. <P>SOLUTION: This partial plating method comprises the steps of: forming a photoreactive layer 2 on the surface of an article 1 to be plated; selectively exposing the photoreactive layer 2 to ultra-violet rays UV; removing an exposed part of the photoreactive layer 2 from the surface of the article 1; imparting a catalyst 4 to the part of the article 1, in which the photoreactive layer 2 has been removed; and forming the electroless-plated film 5 on the part of the article 1, to which the catalyst 4 has been imparted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention provides a partial plating method for partially forming an electroless plating film on the surface of an object to be plated, and a circuit pattern made of an electroless plating film on a circuit board by using such a partial plating method. The present invention relates to a method for manufacturing a circuit board.

  Conventionally, when a circuit pattern made of an electroless plating film is formed on a circuit board, first, an electroless plating film is formed on the surface of a base material to be the circuit board by an electroless plating method. Next, a resist layer patterned by a photolithography technique is formed on the electroless plating film. Next, after etching the electroless plating film using this resist layer as a mask, the resist layer is removed. Thereby, the circuit pattern which consists of an electroless-plating film patterned by the predetermined shape can be formed on a circuit board. In addition, by forming a resist layer patterned by photolithography technology on the surface of a base material to be a circuit board, and forming an electroless plating film thereon by an electroless plating method, the resist layer is lifted off, A circuit pattern made of an electroless plating film patterned in a predetermined shape can also be formed on the circuit board.

  However, in any case, after the plating film is formed over the entire surface, this plating film is partially removed according to the pattern. Therefore, the plating film lifted off after plating or the plating film removed by etching. Has the disadvantage of becoming useless. In addition, when the resist layer is removed from the plating film after etching, or when the resist layer is lifted off after plating, the resist layer is not completely removed or the surface of the plating film is roughened. There are also drawbacks.

  Therefore, a partial plating method has been proposed in which a plating film is formed directly on the surface of a substrate according to a predetermined shape without patterning the plating film after plating (see, for example, Patent Document 1). Specifically, in the partial plating method described in Patent Document 1, first, one or several photosensitive silane monolayers are formed on the surface of an oxide substrate. Next, this photosensitive silane layer is exposed according to a pattern. Next, the exposed portion is esterified with an alcohol having at least one fluorine atom to render the exposed portion highly hydrophobic. Next, the unexposed area is exposed to make it hydrophilic. Next, this hydrophilic area is metallized by an electroless method to form a metal pattern. According to the partial plating method as described above, since the plating film can be formed only in the hydrophilic area, the surface of the oxide substrate can be directly plated according to the pattern.

However, in the partial plating method described in Patent Document 1, a general-purpose copper plating solution is strongly basic, and the above-described photosensitive silane monolayer may be hydrolyzed by the copper plating solution. For example, a copper plating film necessary for forming a circuit pattern on a circuit board cannot be formed. In addition, when the above-mentioned unexposed area is exposed, there is a possibility that a part of the exposed portion esterified by the first exposure may become hydrophilic, so that a circuit pattern cannot be formed on the circuit board with high accuracy. .
JP-A-6-202343

Therefore, the present invention has been made in view of such problems, and its purpose is to provide a partial plating method capable of accurately partially plating an electroless plating film having excellent adhesion on the surface of an object to be plated. There is to do.
Another object of the present invention is to provide a circuit board manufacturing method capable of forming a circuit pattern made of an electroless plating film on a circuit board with high accuracy by using such a partial plating method. It is in.

The partial plating method according to the present invention includes a photoreactive layer forming step of forming a photoreactive layer on the surface of an object to be plated at least having an oxide surface, an exposure step of selectively exposing the photoreactive layer with ultraviolet rays, A removal step of removing the exposed portion of the photoreactive layer from the surface of the object to be plated, a catalyst applying step of applying a catalyst to the portion of the object to be plated where the photoreactive layer has been removed, and a catalyst of the object to be plated were provided. And an electroless plating step of forming an electroless plating film on the portion.
In the photoreactive layer forming step, a photosensitive silane monomolecular film that becomes a photoreactive layer is formed on the surface of the object to be plated using a silane coupling agent containing trifluorosilane.
The silane coupling agent contains trifluoromethoxysilane or trifluoroethoxysilane.
Further, the object to be plated is an inorganic oxide composed of glass, ceramics, or a mixed base material containing one or more of these.
In the exposure step, a mask is arranged on the object to be plated and irradiated with ultraviolet rays, and the mask pattern is projected and exposed to the photoreactive layer.
In the removing step, a photoreactive layer is prepared using a solution selected from dilute hydrofluoric acid, buffered hydrofluoric acid, a mixed liquid of hydrofluoric acid and hydrogen peroxide, and a mixed liquid of hydrofluoric acid and iodic acid. The exposed portion is removed.
In the catalyst application step, metal palladium is applied as a catalyst.
Further, in the electroless plating step, at least one or two or more types of electroless plating films selected from a copper plating film, a nickel plating film, and a gold plating film are provided on the portion of the object to be plated that is provided with the catalyst. It is characterized by forming.
In the electroless plating step, an electroless copper plating film is formed on a portion of the object to be plated with a catalyst using a copper plating solution containing Ni ions.
Moreover, after the electroless-plating process, the heat processing process of heat-processing with respect to a to-be-plated object is included.
In the heat treatment step, the object to be plated is heat-treated in an inert gas atmosphere or a vacuum atmosphere at a temperature of 200 ° C. or higher and lower than the glass transition temperature of the object to be plated.
In the heat treatment step, the heat treatment time is in the range of 10 minutes to 12 hours.
The circuit board manufacturing method according to the present invention is characterized in that a circuit pattern made of an electroless plating film is formed on a circuit board using the partial plating method according to the present invention.

As described above, in the partial plating method according to the present invention, the photoreactive layer is formed on the surface of the object to be plated, the photoreactive layer is selectively exposed with ultraviolet rays, and the exposed part of the photoreactive layer is plated. The electroless plating film is formed by applying a catalyst to the portion where the photoreactive layer of the object to be plated is removed and forming an electroless plating film on the portion where the catalyst is applied. Partial plating can be performed with high accuracy on the surface of the object to be plated.
Moreover, in the method for manufacturing a circuit board according to the present invention, by using such a partial plating method, a circuit pattern made of an electroless plating film can be formed on the circuit board with high accuracy.

  Hereinafter, a partial plating method and a circuit board manufacturing method to which the present invention is applied will be described in detail with reference to the drawings.

  As shown in FIG. 1, a partial plating method to which the present invention is applied is a circuit board in which a circuit pattern such as a wiring made of an electroless copper (Cu) plating film is formed on an inorganic oxide substrate 1 to be a circuit board. Used in the manufacturing method. For the inorganic oxide substrate 1, for example, glass, ceramics, or a mixed base material including one or more of these can be used. In addition, the inorganic oxide is not necessarily limited to such a substrate shape, and may be processed into a predetermined shape. Furthermore, as the object to be plated, it is sufficient that at least the surface is made of an oxide, and if there is oxygen on the surface, even if it is a metal or an organic material, partial plating described later can be performed.

  And before performing partial plating on this inorganic oxide substrate 1, as a process for arranging many OH groups on the surface of the inorganic oxide substrate 1, acid (sulfuric acid / hydrogen peroxide), alkali, hot water (pure water) Desirably, the inorganic oxide substrate 1 is subjected to ultrasonic cleaning using UV or the like or cleaning using ultraviolet rays. This removes oils and fats and the like that hinder adhesion from the surface of the inorganic oxide substrate 1 and forms a substrate on which a silane coupling agent, which will be described later, firmly adheres to and binds to the surface of the inorganic oxide substrate 1. I can leave.

  When performing partial plating on the surface of the inorganic oxide substrate 1, first, as the photoreactive layer forming step shown in FIG. 2, the photoreactive layer 2 is formed on the surface of the inorganic oxide substrate 1. Specifically, a photosensitive silane monomolecular film that becomes the photoreactive layer 2 is formed on the surface of the inorganic oxide substrate 1 using a silane coupling agent. As the silane coupling agent, those containing trifluorosilane such as trifluoromethoxysilane and trifluoroethoxysilane such as trifluoropropyltrimethoxysilane and trifluoropropyltriethoxysilane can be used.

  Next, as an exposure process shown in FIG. 3, a mask 3 is arranged on the inorganic oxide substrate 1 on which the photoreactive layer 2 is formed and irradiated with ultraviolet UV, and the pattern of the mask 3 is projected onto the photoreactive layer 2. Exposure. The mask 3 is provided with an opening 3a having a shape corresponding to the circuit pattern described above. Therefore, the photoreactive layer 2 is selectively exposed by the ultraviolet rays UV that pass through the openings 3 a of the mask 3.

  Next, as the removing step shown in FIG. 4, the exposed portion of the photoreactive layer 2 is removed from the surface of the inorganic oxide substrate 1 by washing. Specifically, in the photosensitive silane monomolecular film forming the photoreactive layer 2, the unexposed portion remains on the inorganic oxide substrate 1 while maintaining super water repellency, and the exposed portion is decomposed by ultraviolet UV. The inorganic oxide substrate 1 is removed by cleaning. For this cleaning, for example, a solution such as dilute hydrofluoric acid, buffered hydrofluoric acid, a mixed liquid of hydrofluoric acid and hydrogen peroxide, a mixed liquid of hydrofluoric acid and iodic acid, or the like can be used.

  Next, as the catalyst application step shown in FIG. 5, the portion of the inorganic oxide substrate 1 from which the photoreactive layer 2 has been removed by immersing the inorganic oxide substrate 1 in a catalyst solution containing palladium (Pd), for example. At least metal palladium is added as catalyst 4 to the catalyst. Specifically, the portion of the inorganic oxide substrate 1 from which the photoreactive layer 2 has been removed becomes a good surface for applying the catalyst 4 by the above-described cleaning, while the photoreactive layer 2 of the inorganic oxide substrate 1 is The remaining portion (the unexposed portion of the photoreactive layer 2) is prevented from adhering to the catalyst 4 by the photosensitive silane monomolecular film having super water repellency. Thereby, the catalyst 4 can be provided only to the portion of the inorganic oxide substrate 1 from which the photoreactive layer 2 has been removed. Examples of the catalyst treatment include a catalyst treatment using a solution containing tin chloride and a solution containing palladium chloride, and a catalyst treatment using a colloidal solution of palladium chloride and tin chloride. .

  Next, as the electroless plating step shown in FIG. 6, the inorganic oxide substrate 1 was immersed in a copper plating solution containing, for example, nickel (Ni) ions, whereby the catalyst 4 of the inorganic oxide substrate 1 was applied. An electroless copper plating film 5 is formed on the portion. Thereby, the electroless copper plating film 5 can be partially plated on the portion of the inorganic oxide substrate 1 provided with the catalyst 4.

  Next, as a heat treatment step shown in FIG. 7, heat treatment is performed on the inorganic oxide substrate 1 on which the electroless copper plating film 5 is partially plated. Specifically, the inorganic oxide 1 is preferably heat-treated in an inert gas atmosphere or a vacuum atmosphere at a temperature of 200 ° C. or higher and lower than the glass transition temperature of the inorganic oxide substrate 1. . The heat treatment time is desirably in the range of 10 minutes to 12 hours. And by performing heat processing on such conditions, the adhesive force with respect to the inorganic oxide board | substrate 1 of the electroless copper plating film 5 can be expressed.

As described above, in the partial plating method to which the present invention is applied, the photoreactive layer 2 is formed on the inorganic oxide substrate 1, the photoreactive layer 2 is selectively exposed with ultraviolet UV, and the photoreactive layer 2 The exposed portion is removed from the inorganic oxide substrate 1, the catalyst 4 is applied to the portion of the inorganic oxide substrate 1 where the photoreactive layer 2 is removed, and the electroless copper plating is applied to the portion where the catalyst 4 is applied. By forming the coating 5, the electroless copper plating coating 5 can be partially plated with high precision on the inorganic oxide substrate 1.
Further, in this partial plating method, even when the photoreactive layer 2 made of a silane monomolecular film may be hydrolyzed by the strongly basic copper plating solution in the electroless plating step, the electroless copper plating film 5 is formed only on the portion of the inorganic oxide substrate 1 to which the catalyst 4 is applied. Therefore, the electroless copper plating film 5 is formed on the inorganic oxide substrate 1 regardless of the hydrolysis of the photoreactive layer 2. The portion plated with the catalyst 4 can be partially plated with high accuracy.
Moreover, in this partial plating method, the adhesive force with respect to the inorganic oxide board | substrate 1 of the electroless copper plating film 5 can be improved by passing through the said heat processing process.

  As described above, in the partial plating method to which the present invention is applied, the electroless copper plating film 5 excellent in adhesion can be partially plated on the inorganic oxide substrate 1 with high accuracy. Further, in the method for manufacturing a circuit board to which the present invention is applied, by using such a partial plating method, an inorganic oxide substrate 1 which becomes a circuit board from a circuit pattern made of an electroless copper plating film 5 having excellent adhesion. It can be formed on the top with high accuracy.

  In the partial plating method to which the present invention is applied, in the electroless plating step, the portion of the inorganic oxide substrate 1 to which the catalyst 4 is applied is applied to the nickel plating film in addition to the electroless copper plating film 5 described above. Alternatively, a gold plating film or at least two or more electroless plating films selected from these can be formed.

Hereinafter, the effects of the present invention will be clarified by examples. However, the following examples do not limit the technical scope of the present invention.
Example 1
In Example 1, first, a borosilicate glass substrate having a diameter of 100 mm and a thickness of 0.7 mm was prepared as an object to be plated, and this substrate was placed in a sodium hydroxide (NaOH) aqueous solution having a concentration of 6.5% at a temperature of 50 ° C. The substrate surface was cleaned by immersing for 3 minutes and then rinsing. Next, the substrate is immersed in a 0.01% by volume trifluoropropyltrimethoxysilane aqueous solution for 3 minutes, rinsed, and this substrate is heat treated at a temperature of 120 ° C. for 1 hour, so that the surface of the substrate is exposed to light. A functional silane monomolecular film was formed. Next, the substrate was irradiated with ultraviolet light having a wavelength of 172 nm at an intensity of 10 mW / cm ² for 5 minutes. Next, the substrate was immersed in a hydrochloric acid acidic solution containing a tin chloride aqueous solution having a concentration of 1.33% and hydrochloric acid having a concentration of 0.54% for 3 minutes at room temperature and rinsed, and then palladium chloride having a concentration of 0.015%. By immersing in an aqueous solution at a temperature of 30 ° C. for 2 minutes and rinsing, metal palladium was applied to the surface of the substrate as a catalyst. Next, about 0.25 g / L (0.0039 mol / L) of copper, about 0.023 g / L (0.00039 mol / L) of nickel are added, and about 0.2% formaldehyde is included as a reducing agent, The surface of this substrate was immersed in a plating bath containing sodium potassium tartrate tetrahydrate (Rochelle salt) as a complexing agent and containing about 0.1% of a chelating agent at a temperature of 36 ° C. for 1 hour. An electroless copper plating film having a thickness of about 2.0 μm was formed. The pH of the plating solution was adjusted with NaOH, and the pH was adjusted to about 12.6 by adding about 1.5 g / L. Next, the substrate was heat-treated at a temperature of 300 ° C. for 1 hour in a vacuum atmosphere of about 1 Torr.

(Example 2)
In Example 2, first, a borosilicate glass substrate having a diameter of 100 mm and a thickness of 0.7 mm was prepared as an object to be plated, and this substrate was placed in a sodium hydroxide (NaOH) aqueous solution having a concentration of 6.5% at a temperature of 50 ° C. The substrate surface was cleaned by immersing for 3 minutes and then rinsing. Next, the substrate is immersed in a 0.01% by volume trifluoropropyltrimethoxysilane aqueous solution for 3 minutes, rinsed, and this substrate is heat treated at a temperature of 120 ° C. for 1 hour, so that the surface of the substrate is exposed to light. A functional silane monomolecular film was formed. Next, a mask was placed on the substrate, and ultraviolet rays having a wavelength of 172 nm were irradiated at an intensity of 10 mW / cm ² for 5 minutes, and the pattern of this mask was projected and exposed to a photosensitive silane monomolecular film. Next, the substrate was immersed in a dilute hydrofluoric acid aqueous solution having a concentration of 0.5% for 1 minute and rinsed to remove the exposed portion of the photosensitive silane monomolecular film from the surface of the substrate by washing. Next, the substrate was immersed in a hydrochloric acid acidic solution containing a tin chloride aqueous solution having a concentration of 1.33% and hydrochloric acid having a concentration of 0.54% for 3 minutes at room temperature and rinsed, and then palladium chloride having a concentration of 0.015%. By immersing in an aqueous solution at a temperature of 30 ° C. for 2 minutes and rinsing, metal palladium was applied as a catalyst to the portion of the substrate where the photosensitive silane monomolecular film was removed. Next, about 0.25 g / L (0.0039 mol / L) of copper, about 0.023 g / L (0.00039 mol / L) of nickel are added, and about 0.2% formaldehyde is included as a reducing agent, The substrate catalyst was immersed in a plating bath containing sodium potassium tartrate tetrahydrate (Rochelle salt) as a complexing agent and containing about 0.1% of a chelating agent at a temperature of 36 ° C. for 1 hour. An electroless copper plating film having a film thickness of about 2.0 μm was formed on the portion provided with. The pH of the plating solution was adjusted with NaOH, and the pH was adjusted to about 12.6 by adding about 1.5 g / L. Next, the substrate was immersed in an aqueous palladium chloride solution having a concentration of 0.015% at a temperature of 30 ° C. for 2 minutes, and then rinsed to give metallic palladium as a catalyst to the portion of the substrate on which the electroless copper plating film was formed. . Next, the substrate is immersed in Ni-P plating solution (Nicolon GM-MP manufactured by Okuno Pharmaceutical Co., Ltd.) for 20 minutes at a temperature of 80 ° C., so that the portion of the substrate on which the electroless copper plating film is formed is applied. An electroless nickel plating film was formed. Further, the substrate is immersed in a gold plating solution (Muden Noble manufactured by Okuno Seiyaku Kogyo Co., Ltd.) for 10 minutes at a temperature of 60 ° C., so that the electroless gold plating film is formed on the portion of the substrate where the electroless nickel plating film is formed. Formed. Next, the substrate was heat-treated at a temperature of 300 ° C. for 1 hour in a vacuum atmosphere of about 1 Torr.

  When the adhesion strength of the plating film formed on each substrate of Example 1 and Example 2 as described above was measured, the adhesion force exceeding 50 MPa was obtained. For the measurement of the adhesion, Sebastian IV type manufactured by QUAD GROUP was used and contacted with a standard stud pin. From the above, it can be seen that in Example 1 and Example 2, the plating film has sufficient adhesion.

  Note that the partial plating method to which the present invention is applied is not necessarily limited to the case where the circuit pattern is formed on the circuit board described above, but is widely used when the electroless plating film is partially plated on the surface of the object to be plated. Can be applied. Further, the present invention is not limited to the above-described partial plating, and can be applied to the case where an electroless plating film is formed over the entire surface of the object to be plated.

FIG. 1 is a view for explaining a partial plating method to which the present invention is applied, and is a sectional view showing an inorganic oxide substrate. FIG. 2 is a view for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state in which a photoreactive layer is formed on an inorganic oxide substrate. FIG. 3 is a view for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state in which a photoreactive layer is selectively exposed with ultraviolet rays. FIG. 4 is a diagram for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state where an exposed portion of the photoreactive layer is removed from the inorganic oxide substrate. FIG. 5 is a diagram for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state in which a catalyst is applied to a portion of the inorganic oxide substrate from which the photoreactive layer has been removed. FIG. 6 is a view for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state in which an electroless copper plating film is formed on a portion of the inorganic oxide substrate provided with a catalyst. FIG. 7 is a diagram for explaining a partial plating method to which the present invention is applied, and is a cross-sectional view showing a state in which a heat treatment is performed on an inorganic oxide substrate.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Inorganic oxide substrate, 2 ... Photoreaction layer, 3 ... Mask, 4 ... Catalyst, 5 ... Electroless copper plating film

Claims (13)

A photoreactive layer forming step of forming a photoreactive layer on the surface of the object to be plated at least having an oxide surface;
An exposure step of selectively exposing the photoreactive layer with ultraviolet rays;
A removal step of removing the exposed portion of the photoreactive layer from the surface of the object to be plated;
A catalyst application step of applying a catalyst to the portion of the object to be plated from which the photoreactive layer has been removed;
A partial plating method including an electroless plating step of forming an electroless plating film on a portion of the object to be plated to which the catalyst is applied.   In the photoreactive layer forming step, a photosensitive silane monomolecular film to be the photoreactive layer is formed on the surface of the object to be plated using a silane coupling agent containing trifluorosilane. Item 2. The partial plating method according to Item 1.   The partial plating method according to claim 2, wherein the silane coupling agent contains trifluoromethoxysilane or trifluoroethoxysilane.   The partial plating method according to claim 2 or 3, wherein the object to be plated is an inorganic oxide composed of glass, ceramics, or a mixed base material containing one or more of them.   4. The partial plating method according to claim 2, wherein, in the exposure step, a mask is arranged on the object to be plated and irradiated with ultraviolet rays, and the pattern of the mask is projected and exposed onto the photoreactive layer. 5. .   In the removing step, the photoreactive layer is formed using a solution selected from dilute hydrofluoric acid, buffered hydrofluoric acid, a mixed liquid of hydrofluoric acid and hydrogen peroxide, and a mixed liquid of hydrofluoric acid and iodic acid. 4. The partial plating method according to claim 2, wherein the exposed portion is removed.   The partial plating method according to claim 2 or 3, wherein in the catalyst application step, metal palladium is applied as the catalyst.   In the electroless plating step, at least one or two or more types of electroless plating films selected from a copper plating film, a nickel plating film, and a gold plating film are provided on the portion of the object to be plated that is provided with the catalyst. The partial plating method according to claim 2, wherein the partial plating method is formed.   In the said electroless-plating process, an electroless copper plating film is formed in the part to which the said catalyst of the said to-be-plated object was provided using the copper plating solution containing Ni ion. The partial plating method described.   The partial plating method according to claim 2, further comprising a heat treatment step of performing a heat treatment on the object to be plated after the electroless plating step.   The heat treatment step is characterized in that the object to be plated is heat-treated in an inert gas atmosphere or a vacuum atmosphere at a temperature of 200 ° C. or higher and lower than the glass transition temperature of the object to be plated. The partial plating method as described in.   The partial plating method according to claim 10, wherein, in the heat treatment step, a heat treatment time is in a range of 10 minutes to 12 hours.   The manufacturing method of the circuit board which forms the circuit pattern which consists of the said electroless-plating film on the circuit board using the partial plating method of any one of the said Claims 1-12.

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