JPH1018044A - Sheet for forming electroless plating layer, sheet with electroless plating layer, photosensitive sheet and formation of metallic pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a novel method for formation of metallic patterns which improves the method for formation of the metallic patterns by utilizing a transfer method. SOLUTION: This sheet for forming an electroless plating layer is obtd. by forming the substrate for electroless plating dispersed with the particulates of a metal or metal compd. and the particulates of tin oxide on a swellable aq. resin layer disposed on the surface of a plastic film 11. This method for forming the metallic patterns successively executes a stage for forming resist patterns 15a on the electroless plating layer by exposing and developing the photoresist layer 15 of the photosensitive sheet 21 obtd. by forming the electroless plating layer 14 and the photoresist layer 15 on the sheet for forming the electroless plating layer, a stage for forming the electrolytic plating layer 23 in the regions where the resist does not exist, a stage for simultaneously transferring the resist patterns 15a and the plating layer on a substrate and a stage for stripping the plastic film 11.

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 metal pattern, a photosensitive sheet which can be advantageously used in the method for forming a metal pattern, and an electroless plating layer used for producing the photosensitive sheet. The present invention relates to a sheet and a sheet for forming an electroless plating layer.

[0002]

2. Description of the Related Art In recent years, electronic devices have become smaller and lighter, and there has been a growing demand for higher density and multi-layered metal wiring such as printed wiring boards. For example, as a method of manufacturing a printed wiring board, a subtractive method using etching typified by a panel plating method or a pattern plating method or an additive method typified by a full additive method is known. Of these, the subtractive method is
It is necessary to form wiring of metal such as copper by etching. However, in the etching method, since the side etching or the like occurs, the cross section of the wiring tends to be trapezoidal. Is not suitable. Further, in the etching method, the metal utilization efficiency is low, and there is a problem in treating a large amount of etching waste liquid generated.

On the other hand, in the additive method, a metal such as copper is selectively deposited by electroless plating on a region of a wiring negative pattern (negative pattern corresponding to the wiring pattern) formed on a substrate using a photoresist. This is a method of generating a wiring pattern by deposition. This method differs from the subtractive method, which has the problem of side etching,
There is an advantage that the limit of the wiring width is relaxed, so that a high-density wiring pattern can be formed. In addition, since the etching treatment is not performed, there is no problem in treating the waste liquid of the etching treatment, and the utilization efficiency of the metal is increased. However, the formation of the wiring pattern by electroless plating takes time, and there is a problem that the production efficiency is not good. Further, in order to perform electroless plating on a wiring substrate, complicated pretreatments such as degreasing, acid treatment, application of a plating catalyst, and activation of the substrate surface are required. For this reason, as an alternative to the method using electroless plating, a conductive support is used on the surface, and a wiring negative pattern is formed with a photoresist on the surface. 2. Description of the Related Art A transfer method for manufacturing a printed wiring board by forming a metal layer such as copper by an electrolytic plating method and transferring the layer to an insulating substrate has been developed. This transfer method does not have the above-mentioned problems caused by etching, and has the advantage that a high-density wiring pattern can be manufactured in a short time because the time required for forming the metal layer is short.

The above transfer method is disclosed in, for example,
No. 187695. In the transfer method described in this publication, a resist pattern is formed on a conductive substrate (support) such as a stainless steel sheet, and then an electroplating layer is formed on an exposed portion of the conductive substrate. This is a method of transferring a resist pattern and an electroplating layer together on a substrate. JP-A-63-283886 discloses that a resist having a conductive film (for example, a metal film layer formed on a film surface by a vacuum deposition or a plasma beam deposition method via a release layer) is formed on a film surface. A method is described in which a pattern is formed, then an electrolytic or electrolytic plating layer is provided on an exposed portion of the conductive film, and finally, the plating layer is transferred to an insulating substrate.

In Japanese Patent Application Laid-Open No. Hei 2-126991, a photoresist layer is formed on a copper-plated support such as a metal tape, and the photoresist layer is photo-etched to form a resist pattern. Apply copper plating to the resist removal area, roughen the surface of the copper plating layer, remove the resist pattern, bond the copper plating layer on the insulated substrate with the adhesive layer down, and finally support A method of forming a metal pattern on an insulating substrate by a method of removing a body is described.

[0006] Among the above methods, the method using a metal sheet or a metal tape as a support (substrate) for forming a metal layer first is expensive because the metal sheet or the metal tape is expensive and heavy. In addition to the problem of poor economy and workability, when the metal layer formed on the metal sheet or the like is transferred to the insulating substrate, it is difficult for the metal sheet or the like to peel off from the metal layer smoothly. There is also a disadvantage. Further, there is a problem that formation of a metal layer using a vapor deposition method or the like is time-consuming and lacks workability and economic efficiency.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a novel method for forming a metal pattern, which is an improved method for forming a metal pattern using a transfer method. Another object of the present invention is to provide a method for forming a metal pattern which is excellent in economy and economy and has a high surface smoothness. Another object of the present invention is to provide an improved method of forming a metal pattern using a transfer method suitable for a method of manufacturing a printed wiring board. Further, the present invention provides a photosensitive sheet that can be advantageously used in carrying out a method for forming a metal pattern using a transfer method, a sheet with an electroless plating layer used for producing the photosensitive sheet, and an electroless plating layer Providing a forming sheet;
In particular, an object of the present invention is to provide a sheet for forming an electroless plating layer having an electroless plating base layer capable of forming an electroless plating layer at an extremely high speed.

[0008]

According to the present invention, there is provided an electroless plating underlayer in which fine particles of a metal or a metal compound and fine particles of tin oxide are dispersed in a swellable aqueous resin provided on the surface of a plastic film. The sheet for forming an electroless plating layer is obtained.

The preferred embodiment of the sheet for forming an electroless plating layer of the present invention is as follows. 1) Tin oxide contains antimony. 2) An undercoat layer made of an adhesive resin is provided between the base layer for electroless plating and the surface of the plastic film. 3) An undercoat layer contains the tin oxide, and the tin oxide is supplied from the undercoat layer to the base layer for electroless plating in contact. 4) The swellable aqueous resin is a crosslinked aqueous resin. Further, the sheet for forming an electroless plating layer of the present invention is a plastic film, an undercoat layer in which fine particles of tin oxide are dispersed in an adhesive resin provided on the surface thereof, and a swelling layer on the undercoat layer. A sheet for forming an electroless plating layer in which fine particles of a metal or a metal compound are dispersed in an aqueous resin layer to form a base layer for electroless plating may be used.

Further, the present invention provides a sheet with an electroless plating layer, wherein the electroless plating layer is formed on an electroless plating base layer of the above-mentioned sheet for forming an electroless plating layer, and the sheet with the electroless plating layer. There is also a photosensitive sheet in which a photoresist layer is formed on an underlayer for electroless plating.

The present invention also provides a step of forming a resist pattern on the electroless plating layer by exposing the photoresist layer of the photosensitive sheet in a pattern and then developing the photoresist layer; Forming a metal pattern on the substrate by sequentially performing a step of forming an electrolytic plating layer on the exposed surface of the plating layer; a step of simultaneously transferring the resist pattern and the plating layer onto the substrate; and a step of peeling off the plastic film. There is also a method. Preferred embodiments of the method for forming a metal pattern of the present invention are as follows. 1) The method further includes a step of etching the surface of the metal pattern formed on the substrate to smooth the surface of the plating layer. 2) The underlayer for electroless plating and the electroless plating layer of the photosensitive sheet are integrated, the boundary between them is not clear, and the metal phase of the electroless plating layer part becomes the underlayer part for electroless plating. Up to the lower part of the electroless plating layer.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the photosensitive sheet used in the present invention, the sheet for forming an electroless plating layer used for preparing the photosensitive sheet and the sheet with the electroless plating layer, and the present invention using the photosensitive sheet are described. The method for forming the metal pattern will be described in detail. The photosensitive sheet used in the metal pattern forming method of the present invention is used for electroless plating in which fine particles of a metal or a metal compound and fine particles of tin oxide are dispersed in a swellable aqueous resin provided on the surface of a plastic film. It has a configuration in which an electroless plating layer and a photoresist layer are formed on a base layer in this order. In manufacturing the photosensitive sheet, first, a base film for electroless plating in which fine particles of a metal and a metal compound as a starting material for forming the metal are dispersed in a swellable aqueous resin on a plastic film. A sheet for forming an electroless plating layer is prepared.

FIG. 1 shows the structure of a sheet for forming an electroless plating layer.
Is shown schematically in FIG. In FIG. 1, a sheet 10 for forming an electroless plating layer includes a plastic film (functioning as a support) 11, an undercoat layer 12 made of a hydrophobic binder, and fine particles of a metal and a metal compound dispersed in a swellable aqueous resin. The electroless plating base layer 13 is formed.
The material for forming a plastic film used as a support in the sheet for forming an electroless plating layer is not particularly limited. For example, cellulose ester, polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, poly-1,4-cyclohexane dimethylene terephthalate, polyethylene-1,2-diphenoxyethane-4,4′-dicarboxylate, polyethylene-1, 6-naphthalate), polystyrene, polyolefin (eg, polypropylene, polyethylene), polyimide, polyamideimide, polyethersulfone, and other plastic materials. These plastic materials may be used as a mixture of two or more kinds, or may be used by laminating films made of the respective plastic materials. Desirably, the plastic film support material described above has high dimensional stability. That is, the plastic film support of the sheet for forming an electroless plating layer of the present invention desirably has a coefficient of thermal expansion of 1 × 10 ⁻⁴ / ° C. or less, and a dimensional change rate of humidity of 1 × 10 ⁻⁴ / ° C.
It is preferably at most ^-4 % RH (particularly at most 1 × 10 ^-5 % RH). Therefore, among the plastic materials described above, polyethylene terephthalate is particularly suitable for use as the support film material of the sheet for forming an electroless plating layer of the present invention, among which biaxially stretched and thermally fixed. Polyethylene terephthalate film is particularly preferable in consideration of economy, dimensional stability, strength, flatness and the like. Further, polyethylene-2,6-naphthalate described in JP-A-6-25916,
Syndiotactic polystyrene (SPS) described in 55615 is also a preferred support material.
There is also no particular limitation on the thickness of the plastic film used as a support in the electroless plating layer forming sheet,
Usually, it is appropriately determined within a range of 6 to 200 μm (particularly, 50 to 180 μm). The plastic film may be transparent or opaque, and, if desired, additives such as dyes and pigments (eg, titanium dioxide), lubricants (eg, silica, calcium carbonate), and fillers. May be included.

The sheet for forming an electroless plating layer is formed by dispersing fine particles of a metal or a metal compound in a swellable aqueous resin, and further dispersing fine particles of tin oxide on a plastic film (support). The main feature is that the base layer for electroless plating is formed, but the base layer for electroless plating is preferably provided on the surface of the plastic film via an undercoat layer made of an adhesive resin. . The undercoat layer mainly has a function of fixing the base layer for electroless plating uniformly and securely on the surface of the plastic film support, and maintaining the uniform fixed state for a long period of time. In the present invention, as described later, this undercoat layer may contain the above-mentioned tin oxide, and in that case, the base layer for electroless plating may not contain tin oxide. As the adhesive resin of the undercoat layer,
Homopolymers or copolymers derived from monomers such as vinyl chloride, vinylidene chloride, methacrylic acid, acrylic acid, methacrylic acid ester, acrylic acid ester, itaconic acid, maleic anhydride, vinyl acetate, butadiene, and styrene Examples include hydrophobic binders and materials obtained by crosslinking them with a crosslinking agent (eg, 2,4-dichloro-6-oxy-S-triazine). Examples thereof include butadiene / styrene copolymer latex and vinylidene chloride latex.
The molecular weight (weight average molecular weight) of the polymer used is 5000
As described above, it is particularly desirable that the number be 20,000 or more and 2,000,000 or less. Further, the melting point is desirably in the range of 120 ° C to 250 ° C.

The thickness of the undercoat layer is usually 0.01 to 5.0 μm.
(Preferably 0.1 to 1.0 μm). The undercoat layer can be formed on the surface of the plastic film support by a general method such as melting and applying an adhesive resin or applying and drying an adhesive resin solution. Prior to the application of the adhesive resin, in order to improve the adhesiveness between the adhesive resin and the surface of the support plastic film, a known surface treatment (eg, corona discharge treatment, glow discharge treatment, It is desirable to perform plasma treatment, flame treatment, and chemical treatment). In addition, it is preferable that the plastic film support after the formation of the undercoat layer has little vertical and horizontal dimensional changes even when stored at a high temperature.

On the plastic film (support) provided with the undercoat layer, fine particles of a metal or a metal compound and fine particles of tin oxide are dispersed in a swellable aqueous resin on the undercoat layer. The underlayer for electroless plating of the present invention is formed. The base layer for electroless plating of the present invention in the sheet for forming an electroless plating layer has a hydrophilic surface, and has a swelling property.When the sheet for forming an electroless plating layer is immersed in an electroless plating solution, The plating solution permeates deep inside the base layer for electroless plating. And, since electroless plating is performed using fine particles of a metal or a metal compound dispersed inside the electroless plating base layer as a nucleus, the electroless plating layer formed on the surface of the base layer is
It is in a state of being firmly bonded to the underlayer. Therefore, an electroless plating layer having sufficient strength to proceed with subsequent processing is formed on the plastic film support.

The underlayer for electroless plating in which fine particles of a metal or a metal compound are dispersed in the above-mentioned swellable aqueous resin and fine particles of tin oxide (preferably containing antimony) are dispersed, Preparing an aqueous solution containing tin oxide and a reducing agent (and, if necessary, a protective colloid), such as a resin, a metal salt or a metal complex,
The metal or metal compound fine particles are precipitated by a reduction reaction of a metal salt or a metal complex or the like in the aqueous solution to form a coating liquid containing the metal or metal compound fine particles and the aqueous resin, and the coating solution is coated on the support surface (or on the support). (Undercoat layer surface) by applying and drying. Alternatively, an aqueous solution containing a swellable aqueous resin, a metal salt or a metal complex, and tin oxide is prepared in advance, and the aqueous solution is applied to the surface of a support (or the surface of an undercoat layer on the support). It can be formed by a method in which a metal salt or metal complex is reduced by infiltrating a reducing agent into the layer to precipitate fine particles of the metal or metal compound, and finally dried. Alternatively, a coating solution containing fine particles of a metal or a metal compound, tin oxide, and an aqueous resin is prepared from the beginning, and the coating solution is applied to the surface of a support (or the surface of an undercoat layer on the support) and dried. It is also possible to form an underlayer for plating.

The metal used is basically conductive, and examples thereof include Au, Pt, Pd, Ag,
Examples include metals such as Cu, Ni, Fe, Ro, Cr, and Sn. Examples of the metal compound include salts, oxides and sulfides of these metals. Specific examples of the metal compound and the starting material include PdS, SnS, Ag ₂ S, P
dCl ₂ , SnCl ₂ , AgCl, PdF ₂ , AgF
₂ , SnF ₂ , PdO ₂ , Ag ₂ O, HAuCl ₄ , H ₂
PtCl ₆ can be mentioned. In addition to the metal salts and metal complexes exemplified above, chlorides, sulfides, fluorides, bromides, iodides, oxides, and various complexes of other metals can be used. Examples of commercially available products include SN-100A and S-100 manufactured by Ishihara Sangyo Co., Ltd.
N-100N and T1 manufactured by Mitsubishi Materials Corporation.

Examples of the reducing agent include sodium hypophosphite, dimethylamine borane, sodium borohydride,
Examples thereof include inorganic or organic reducing agents such as potassium borohydride, formaldehyde, hydrazine, and ascorbic acid.

The resin forming the electroless plating base layer is as follows:
Generally selected from water-soluble resins or polymer latexes, such as gelatin and its derivatives (eg,
Acylated gelatin such as phthalated gelatin and maleated gelatin, and grafted gelatin grafted onto gelatin with acrylic acid, methacrylic acid or amide),
Examples thereof include polymers such as polyvinyl alcohol and its derivatives, polyvinylpyrrolidone and its derivatives, polyacrylic acid, and polyacrylic acid-diacrylate copolymer. These polymers can be used alone or in combination. In addition, a cellulose derivative such as methylcellulose can be used in combination with these polymers in order to reduce the adhesion of the coating film and improve the blocking property. Also, phenol and resorcinol for improving swellability, ionic polymers for preventing adhesion of foreign substances, anionic or cationic surfactants,
An electrolyte such as a maleic acid-based copolymer described in JP-A-3972, colloidal silica, and salt may be added.

The underlayer for electroless plating is preferably crosslinked. That is, a cross-linking agent such as a water-soluble cross-linking agent is added to a coating solution for forming a base layer for electroless plating, and the coating solution is applied to the surface of the support, and then heated to cross-link the coating layer. The strength of the underlayer can be increased. Examples of such a water-soluble crosslinking agent are disclosed in
These are described in JP-A-141347 and JP-A-3-137637. Examples of specific compounds include the following. When the aqueous resin is polyvinyl alcohol, an aldehyde compound such as butyraldehyde or boric acid can be used. When the aqueous resin is an acrylic acid derivative, N-methylol urea or poly-N-methylol acrylamide which reacts with a polyvalent metal ion such as aluminum or zinc or a carboxyl group can be used. In the case of gelatin or a gelatin derivative, US Pat. Nos. 3,325,287 and 3,288,775.
No. 3,549,377, Belgian Patent No. 6,602,226, etc., triazine compounds described in U.S. Pat.
4, dialdehyde compounds described in British Patent No. 1270578 and the like, US Pat.
No. 37, JP-B-49-26580 and the like, epoxy compounds described in US Pat.
No. 86, and the like, and a vinylimine compound or a methylol-based compound described in US Pat. No. 3,392,024 can be used. Particularly preferred crosslinking agents are dichloro-S-triazine derivatives such as 2,4-dichloro-6-hydroxy-S-triazine sodium salt. When the base layer for electroless plating is provided on the plastic film support via an undercoat layer, a crosslinking agent can be introduced into the undercoat layer.

The weight ratio of the aqueous resin to the fine particles of metal or metal compound in the base layer for electroless plating is usually 0.01 to 10000, preferably 0.1 to 1000.
(Aqueous resin / fine particles of metal or metal compound). The size of the fine particles of the metal or metal compound is usually 0.0003 to 10 μm.
(Preferably 0.001 to 1.0 μm). The thickness of the underlayer for electroless plating is usually 0.005 to 5 μm (preferably 0.01 to 1 μm).

The underlayer for electroless plating of the present invention contains fine particles of tin oxide, preferably tin oxide containing antimony, in addition to the fine particles of the metal or metal compound. Tin oxide is preferably added in an amount of 10 to 1000 times the weight of the above-mentioned metal or metal compound.
The amount is preferably from 0 to 500 times. The amount of antimony to tin oxide is generally in the range of 0.1 to 50% by weight,
A range of 20% by weight is preferred, and a range of 6 to 13% by weight is particularly preferred. The average particle diameter of the tin oxide fine particles is preferably 0.01 to 0.5 μm. When electroless plating is performed on the electroless plating base layer containing tin oxide, the formation rate of the obtained plating layer is two to three times or more as compared with the case where the electroless plating is not included, and the desired layer can be formed in a short time. A thick electroless plating layer can be obtained.

The above tin oxide may be contained in the undercoat layer. In this case, the base layer for electroless plating may be a normal layer not containing tin oxide or a layer containing tin oxide. By including tin oxide in the undercoat layer as described above, the formation rate of the plating layer can be increased. This is because the tin oxide contained in the undercoat layer or exposed on the surface and the electroless plating layer formed on the undercoat layer are mixed at the interface, and a portion where both metal and tin oxide are present is formed, This region is considered to contribute to the increase in the formation speed of the plating layer. The weight ratio between the binder resin and tin oxide when tin oxide is contained in the undercoat layer is as follows:
Usually 0.0001-100, preferably 0.001-
It is adjusted to be in the range of 10 (binder resin / tin oxide).

The above-described electroless plating layer is formed on the electroless plating base layer by a known method or a method analogous thereto. There is no particular limitation on the electroless plating solution that can be used, and various commercially available treatment solutions can be used.
Generally, in the case of copper plating, an EDTA bath of copper sulfate or a Rochelle salt bath is used. In the case of nickel plating, an acidic bath using nickel sulfate or nickel chloride, or a low-temperature neutral bath having a liquid temperature of 30 to 60 ° C.,
An ammonia alkali bath, a caustic alkali bath, or the like is used. In the case of cobalt plating, a neutral or alkaline crenic acid bath or a tartaric acid bath using a cobalt salt such as cobalt sulfate or cobalt chloride is used. The thickness of the electroless plating layer is usually 0.1 to 1.0 μm.
m (preferably, 0.2 to 0.5 μm) is selected.

In the present invention, the above-described electroless plating is performed on a base layer for electroless plating containing tin oxide. Thereby, the formation rate of the obtained plating layer is 2-3 times or more as compared with the electroless plating base layer containing no tin oxide, and an electroless plating layer having a desired layer thickness can be obtained in a short time. . In particular, a remarkable effect is obtained in the case of the copper plating.

The electroless plating layer penetrates into the underlayer for electroless plating by the anchor effect as described above, and is formed so as not to be easily separated from the underlayer. That is, when electroless plating (chemical plating) is performed on the surface of a plastic film by a known general method, a physical method such as blasting or a chemical method such as etching using chromium mixed acid is used. It is necessary to perform a surface treatment in advance using the above. When the surface treatment of the plastic film is performed by such a general method, and the electroless plating is performed thereon, the electroless plating layer has no problem in ordinary handling. When performing various processes such as formation of a photoresist layer, elution of an uncured photoresist layer, electrolytic plating, and transfer of a plating layer to a substrate, a plastic film is formed in the middle of the process. This is problematic in that peeling off from the surface tends to occur. On the other hand, in the electroless plating layer formed on the electroless plating underlayer in the present invention, the plating metal phase is generated from inside the electroless plating layer underlayer. The formed electroless plating layer and the electroless plating base layer are integrated while forming a composite structure in which the former leg bites into the latter and exhibits an anchoring effect. The electroless plating base layer is firmly fixed to the plastic film by the effect of the undercoat layer or the like. Therefore, the electroless plating layer in the sheet with the electroless plating layer of the present invention, even during various subsequent processing, without peeling from the plastic film, the first time when the plastic film is peeled off from the substrate in the transfer step, and the plastic film. Become separated.

A photoresist layer is formed on the electroless plating layer. Usually, a negative type is used as the photoresist. Further, in consideration of the simplicity of treatment of the development waste liquid, a photoresist which can be developed with an alkaline aqueous solution is preferable. The photoresist layer may be formed by applying a photoresist solution on the surface of the electroless plating layer by a coating method such as web application, or by laminating a dry film-formed resist film on the surface of the electroless plating layer. They may be stacked. Note that commercially available plating resists, photosensitive solder resists, and the like for the additive method can also be used. A typical example of the photosensitive sheet used in the present invention is a photosensitive sheet having a photosensitive resist prepared as described above on the surface thereof.

Next, a method for forming a metal pattern using the photosensitive sheet of the present invention will be described with reference to the drawings. FIG. 2 is a view schematically showing a step of forming a metal pattern on a substrate according to the metal pattern forming method of the present invention. That is, first, the electroless plating layer forming sheet 10 of the present invention shown in FIG. 1 (a plastic film support 11, an undercoat layer 12 made of a hydrophobic binder, and fine particles of a metal and a metal compound in a swellable aqueous resin). The electroless plating layer 14 and the photoresist layer (photosensitive resist layer) 15 are laminated on the electroless plating base layer 13) in which 21 is manufactured (a).

Next, the photoresist layer 15 of the photosensitive sheet 21 is exposed in a pattern using a photomask 22 having a wiring pattern or the like (b), and then developed to develop the electroless plating layer 14. A resist pattern 15a is formed on the substrate (C). On the exposed surface of the electroless metal plating layer which is partially exposed by the resist pattern 15a formed by the above-described exposure and development, an electrolytic plating layer 23 is formed by a known method or a method analogous thereto next. (D). The electrolytic plating solution used in the present invention is not particularly limited, and a commercially available processing solution or a processing solution similar thereto can be used. Specifically, in the case of copper plating, a low-concentration or high-concentration bath of copper borofluoride, an electroforming bath of copper sulfate, a gloss bath, a general bath, and a gloss bath of copper pyrophosphate may be used. it can. In the case of nickel plating, a trinickel bath using nickel sulfate or nickel chloride, a bright bath Weisberg bath, or the like is used. Of course, the electrolytic plating is not limited to plating of a single metal, but alloy plating can also be used. The electrolytic plating layer formed by the method for forming a metal pattern according to the present invention usually has a thickness in the range of 10 to 50 μm. However, if desired, thicker,
Alternatively, it can be made thin. In consideration of the transfer of the resist pattern and the electrolytic metal plating layer to the substrate in the next step, the thickness of the electrolytic plating layer is preferably substantially equal to the thickness of the resist pattern.

Next, the resist pattern and the electrolytic plating layer formed as described above are simultaneously transferred onto the substrate 24 (e). As the substrate, a known substrate or a substrate similar thereto is used. Examples thereof include a plastic film substrate such as a polyimide film and a composite material substrate such as a glass epoxy substrate.
Note that the substrate need not necessarily be in the form of a film or sheet. The transfer of the resist pattern and the electrolytic plating layer to the substrate is usually performed by providing an adhesive layer 25 on the surface of the substrate and then laminating the resist pattern and the electrolytic plating layer on the surface of the adhesive layer. Then pressurize and heat
A bonding method is used. In this case, the adhesive is made of a material such as a urea resin, a melamine resin, a phenol resin, or an epoxy resin, and a hot melt adhesive or a thermosetting adhesive is used. A commercially available photocurable solder resist can also be used. The adhesive may be an adhesive sheet formed into a dry film.

Then, after the above-mentioned transfer is completed, the plastic film of the photosensitive sheet is manually removed from the laminate by using a hand.
Alternatively, the target metal pattern can be obtained by mechanically peeling off (f) (g). If desired, the resist pattern remaining on the substrate can be removed by a method such as dissolution. In order to further improve the smoothness or gloss of the surface of the metal pattern formed on the substrate, the surface may be subjected to a soft etching treatment. This soft etching process
This is a known method, and can be carried out, for example, by treating the target metal surface with an aqueous solution of about 5 to 10% of an oxidizing agent such as ammonium persulfate or sodium persulfate for several tens seconds to several minutes.

In the above method for forming a metal pattern,
After the electrolytic plating layer 23 is formed (d), the resist pattern 15a is removed first, and then the same operation as (e) and (f) is performed to form a metal pattern having no resist pattern. Can also. Further, a similar metal pattern may be formed on the back side of the substrate 24.

The substrate having a metal pattern on the surface obtained as described above can be used alone as it is, but if desired, two or more sheets can be laminated to form a multilayer. The multi-layering can be easily performed by using, for example, a known prepreg.

[0035]

【Example】

[Example 1] (1) Preparation of a sheet for forming an electroless plating layer 1) A surface of a polyethylene terephthalate (PET) film (thickness: 100 µm) was subjected to a corona discharge treatment, and a coating liquid having the following composition was applied to the treated surface. , Application amount is about 6
The solution was applied using a wire bar so as to be mL / m ^2, and dried at 170 ° C. for 1 minute to form an undercoat layer.

[Undercoat Layer Composition] Butadiene / styrene copolymer latex (solid content 43%, butadiene / styrene weight ratio = 32/68) 13 mL 2,4-dichloro-6-hydroxy-S-triazine sodium salt ( 1.6% aqueous solution of cross-linking agent) 9mL 1% aqueous solution of sodium laurylbenzenesulfonate 1.6mL Distilled water 78mL 2) The surface of the undercoat layer on the above polyethylene terephthalate film is subjected to corona discharge treatment, and then the treated surface A coating solution prepared as described below was applied to a coating amount of about 9 m.
L / m ² using a wire bar to apply,
After drying at 150 ° C. for 2 minutes, an electroless plating underlayer was formed.

[Preparation of coating solution for forming electroless plating base layer] Solution A) 0.02 g of palladium chloride (manufactured by Wako Pure Chemical Industries, Ltd.)
Is completely dissolved in a mixture of 0.1 g of 5N hydrochloric acid and 11.3 g of pure water. Solution B) 1 g of a 1N aqueous sodium hydroxide solution. C solution) It is prepared by dissolving 0.03 g of polyvinylpyrrolidone (K90; manufactured by Tokyo Chemical Industry Co., Ltd.) in 8.75 g of pure water. D solution) formaldehyde (manufactured by Wako Pure Chemical Industries, Ltd.) 0.02
g in 12.5 g of pure water. The above solution C was stirred at 40 ° C. using a stirrer (15
(0 rpm), the solution B is slowly added thereto, and the solution A and the solution D are simultaneously slowly added. The color of the aqueous solution changes with the addition, and a black-brown transparent palladium colloid aqueous solution is obtained. Next, an aqueous solution obtained by heating and dissolving 0.1 g of gelatin (681-Gel; manufactured by Nitta Gelatin Co., Ltd.) in 6.1 g of pure water while stirring the aqueous colloid solution, and an antimony-containing tin oxide dispersion (Sn / S
b = about 9.5 (weight); solid content: 17% by weight) 10 g and 0.033 g of a 2% aqueous solution of cyanuric chloride are added.

(2) Preparation of Sheet with Electroless Plating Layer The sheet for forming electroless plating layer prepared in (1) above
A test piece was prepared by cutting into a square of 0 cm × 20 cm. The test piece was immersed in an electroless copper plating solution having the following composition (Melplate CU390, manufactured by Meltex Corporation) and subjected to an electroless plating operation at about 20 ° C. for 20 minutes. The copper layer (copper plating layer) deposited on the test piece has a metallic luster,
The layer thickness was 0.303 μm, which was almost uniform. Also,
In this plating operation, no detachment of the metal fine particles from the plating layer forming underlayer was observed.

After attaching an adhesive tape to the surface of the copper layer (copper plating layer) thus deposited, a test was conducted to peel off the tape, but no peeling of the copper layer occurred. Also,
The surface resistance of this copper plating layer is measured using a low-resistance surface resistance meter (MCP-TESTER LOREST manufactured by Mitsubishi Yuka Co., Ltd.).
About 0.4 to 0.6 Ω / sq measured using A)
Was obtained. The copper plating layer has a strong red copper color when viewed from the front side, and also has a red copper color when viewed from the back side (PET film side), but has a lower metallic luster than the front side. It was also confirmed that the metallic luster was sparse. That is, the copper plating layer and the electroless plating underlayer are integrated, and the metal phase of the electroless plating layer portion is less sparse than the electroless plating layer portion up to the electroless plating underlayer portion. It was confirmed that the structure had penetrated in the state.

(3) Preparation of photosensitive sheet On the electroless copper plating layer of the sheet with the electroless plating layer,
Alkali-developed photoresist film (A640 manufactured by Fuji Photo Film Co., Ltd.)
A photosensitive sheet was prepared by adhering at 1.0 ° C./min. (4) Formation of negative wiring pattern The surface of the photoresist film of the photosensitive sheet is subjected to pattern exposure using a wiring pattern mask, developed with an alkali developing solution, and formed into an electroless copper plating layer in a wiring pattern. Was exposed to form a wiring negative pattern of resist. (5) Electroplating treatment The sheet treated in the above (4) was immersed in an electrolytic plating solution (a copper sulfate bath to which a brightener, Copperglyme P, manufactured by Reironal Co., was added at a concentration of 5 mL / L), and the temperature was reduced to about 20 ° C. At temperature,
An electric current was passed for 20 minutes under the conditions of 1.2 A / dm ² to form an electrolytic copper plating layer on the surface of the electroless copper plating layer exposed in the above (4).

(6) Transfer of Metal Pattern to Substrate A separately prepared glass epoxy substrate is overlaid with a solder resist film (Bacrel 8030, manufactured by DuPont), 2 kg / cm, 105 ° C., 1.0 m / min. Pasted under the conditions. The sheet having the electroless plating layer obtained in the above (5) is overlaid on the solder resist film on the above-mentioned glass epoxy substrate so that the electroless plating layer is in contact with the resist film surface, and 4 kg / cm. ,
Lamination was performed under the conditions of 120 ° C. and 0.5 m / min, and the laminate was integrated. Next, when the PET film was peeled off from the laminate, the copper plating layer in the form of a wiring pattern and the resist wiring negative pattern were transferred onto the solder resist film on the glass epoxy substrate, and the resolution was about 50 μm. Met. Subsequently, the surface of the transferred copper plating layer was treated with a 12% aqueous solution of ammonium persulfate at 30 ° C. for 2 minutes (soft etching). As a result, a glossy surface of copper appeared and an excellent wiring board was obtained. Was done.

Example 2 In Example 1, an antimony-containing tin oxide dispersion (Sn / Sb) was added to the undercoat layer composition.
= About 9.5 (weight); solid content: 17% by weight), and a tin oxide dispersion was not used and gelatin (681-
Gel; manufactured by Nitta Gelatin Co., Ltd.) A sheet for forming an electroless plating layer was prepared in the same manner as in Example 1 except that the amount of pure water in which 0.1 g of 0.1 g was dissolved was changed from 6.1 g to 16.1 g. Then, in the same manner as in Example 1, an electroless plating layer was formed, and a sheet with an electroless plating layer was formed. The thickness of the electroless plating layer was 0.4 μm, which was almost uniform. further,
Using a sheet with an electroless plating layer, lamination of a resist film, formation of a wiring negative pattern, electrolytic plating operation, and transfer operation were performed in the same manner as in Example 1, and finally a soft etching operation was performed. Wiring pattern copper plating layer with glossy surface (resolution: about 5
0 μm) and a resist negative pattern on the surface were obtained.

[Reference Example 1] In Example 1, a tin oxide dispersion was not used when preparing a coating solution for forming an electroless plating underlayer, and gelatin (681-Gel; manufactured by Nitta Gelatin Co., Ltd.) was used. ) 6.1 g of pure water to dissolve 0.1 g
A sheet for forming an electroless plating layer was prepared in the same manner as in Example 1 except that the thickness was changed from 16.1 g to 16.1 g. Made of sheet. The thickness of the electroless plating layer is 0.
It was almost uniform at 070 μm. The thickness of the electroless plating layer was extremely smaller than the thickness of 0.303 μm in Example 1. Further, using a sheet with an electroless plating layer, laminating a resist film in the same manner as in Example 1,
A wiring negative pattern was formed, an electrolytic plating operation was performed, and a transfer operation was performed. Finally, a soft etching operation was performed, and a copper plating layer having a glossy surface on the surface (resolution: about 50 μm) and a resist negative pattern were formed. Was obtained on the surface of a glass epoxy substrate (wiring substrate). However, in the copper plating layer in the form of a wiring pattern, several small defect regions which were detached and had no copper plating were found.

[0044]

According to the present invention, the electroless plating layer in the photosensitive sheet of the present invention has a moderate strength to the plastic film support by the swellable hydrophilic resin layer thereunder (without peeling by an operation such as electrolytic plating, etc. On the other hand, the plastic film support after transfer is smoothly removed). The photosensitive sheet is obtained by forming an electroless plating layer and a photoresist layer on the electroless plating layer forming sheet of the present invention. The sheet for forming an electroless plating layer of the present invention can remarkably increase the plating rate when performing electroless plating on an underlayer for forming an electroless plating layer. Photosensitive sheet) can be easily prepared in an extremely short time. Further, when a method for forming a metal pattern utilizing a transfer method is performed using the photosensitive sheet of the present invention, it is possible to form a metal pattern having excellent workability and economy and having a high surface smoothness. it can. Therefore,
The method for forming a metal pattern according to the present invention can be particularly advantageously used for manufacturing a high-definition printed wiring board.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of the configuration of an electroless plating layer forming sheet used in a method for forming a metal pattern according to the present invention.

FIG. 2 is a view schematically showing each step of a method for forming a metal pattern of the present invention.

[Explanation of symbols]

 Reference Signs List 10 Sheet for forming electroless plating layer 11 Plastic film 12 Undercoat layer 13 Base layer for electroless plating 14 Electroless plating layer 15 Photoresist layer 15a Resist pattern 21 Photosensitive sheet 22 Photomask 23 Electrolytic plating layer 24 Substrate 25 Adhesive layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yasunori Kobayashi 200 Fujinaka Photo Film Co., Ltd., Fujinomiya City, Shizuoka Prefecture (72) Inventor Masahiro Execution 200 Fujinaka Film Co., Ltd. 200 Onakazato Fujinomiya City, Shizuoka Prefecture

Claims (10)

[Claims] 1. An electroless plating layer formed by forming a base layer for electroless plating in which fine particles of a metal or a metal compound and fine particles of tin oxide are dispersed in a swellable aqueous resin provided on the surface of a plastic film. Sheet. 2. The sheet for forming an electroless plating layer according to claim 1, wherein the tin oxide contains antimony. 3. The electroless plating layer-forming sheet according to claim 1, wherein an undercoat layer made of an adhesive resin is provided between the electroless plating base layer and the surface of the plastic film. 4. The sheet for forming an electroless plating layer according to claim 1, wherein the swellable aqueous resin is a crosslinked aqueous resin. 5. A plastic film, an undercoat layer in which fine particles of tin oxide are dispersed in an adhesive resin provided on the surface of the plastic film, and fine particles of a metal or a metal compound in a swellable aqueous resin on the undercoat layer. A sheet for forming an electroless plating layer, in which is dispersed an underlayer for electroless plating. 6. A sheet with an electroless plating layer, wherein the electroless plating layer is formed on an electroless plating base layer of the electroless plating layer forming sheet according to claim 1. 7. The electroless plating base layer and the electroless plating layer are integrated, the boundary between them is not clear, and the metal phase of the electroless plating layer part extends to the electroless plating base layer part. The sheet with an electroless plating layer according to claim 6, wherein the sheet penetrates in a state less sparse than the electroless plating layer portion. 8. A photosensitive sheet comprising the sheet with an electroless plating layer according to claim 6, wherein a photoresist layer is formed on the electroless plating layer. 9. A step of forming a resist pattern on the electroless plating layer by exposing the photoresist layer of the photosensitive sheet according to claim 8 to a pattern and then developing the photoresist layer; Forming an electrolytic plating layer on the exposed surface of the electrolytic plating layer; simultaneously transferring the resist pattern and the plating layer onto the substrate; and removing the plastic film to form a metal pattern on the substrate. How to let. 10. The method for forming a metal pattern according to claim 9, further comprising a step of etching the surface of the metal pattern formed on the substrate to smooth the surface of the plating layer.