JP2008294059A - Forming method of conductor layer, and manufacturing method of circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form a conductor layer excellent in bonding strength with an insulating base material and having less fault on the insulating base material without requiring an electroless plating step. <P>SOLUTION: The forming method of a conductor layer is provided with an applied film forming step (S1) of applying a solution containing a polyimide precursor resin on the surface of an insulating base material and drying it to form an applied film, an impregnation step (S2) of impregnating the applied film in a solution containing a metal compound to allow metal ions in the solution to impregnate into the surface of the applied film, a metal coating forming step (S3) of executing reduction processing to the metal ions impregnated into the surface of the applied film by the impregnation step and forming a metal coating, and an imidizing step (S5) of executing heat processing to imidize the polyimide precursor resin in the applied film, thereby forming a polyimide resin layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for forming a conductor layer for forming a conductor layer to be a wiring or the like on an insulating substrate used for an electronic component, and a method for manufacturing a circuit board using the method for forming a conductor layer.

  With recent downsizing of electronic components and higher signal transmission speed, high-density wiring is required on circuit boards such as flexible printed boards. In order to realize high-density wiring, it is indispensable to finely process the patterned conductor layer. However, when the conductor layer is finely processed, there is a drawback that the adhesion to the substrate is lowered. Therefore, in order to improve the reliability and yield of electronic components, it has become important to improve the adhesion between the conductor layer and the base material so that it can withstand fine processing.

  As a method for forming a conductive layer having a fine pattern and excellent adhesion to a substrate on a circuit board, Patent Document 1 discloses a metal superfine particle having a fine average particle diameter in a thermosetting resin composition containing an organic solvent. A method using a conductive metal paste in which fine particles are uniformly dispersed is described. In the method of this patent document 1, after apply | coating a conductive metal paste to a board | substrate using an inkjet printing technique, a coating film is heated to the temperature of 150 to 210 degreeC. This heating is performed for the purpose of sintering the metal fine particles to make the coating film conductive and to cure the thermosetting resin. However, in the method of Patent Document 1, if the fine metal particles are not successfully sintered, the conduction of the patterned conductor layer cannot be achieved, and the reliability of the electronic component may be reduced.

  In addition, as a method for forming a patterned conductor layer without using metal fine particles, Patent Document 2 describes a method using a polyimide precursor resin solution containing a palladium ion-containing compound and a polyimide precursor resin. In the method of Patent Document 2, the polyimide precursor resin solution is applied to a polyimide base material by a bar coater or the like, and then the coating film is dried to form a polyimide precursor metal complex layer. Next, the polyimide precursor metal complex layer is irradiated with ultraviolet rays in the presence of a hydrogen donor to form a plating base nucleus, and then a plating base metal layer is formed by electroless plating. Further, after the electroplating layer is formed on the plating base metal layer by electroplating or before the formation, the polyimide precursor resin is heated and imidized to form a polyimide resin layer. Since the technique described in Patent Document 2 does not use a conductive metal paste containing metal fine particles, there is an advantage that a conductor layer can be formed regardless of the sintered state of the metal fine particles. However, the method of Patent Document 2 employs ultraviolet irradiation reduction to reduce metal ions, and has a problem that the reduction efficiency is insufficient.

  Also, as a method of forming a metal layer on the resin surface, after introducing a cation exchange group into the resin substrate, this is treated with a metal ion-containing liquid to chemically adsorb the metal ion to the cation exchange group. A method of performing a reduction treatment after that is also known. When metal ions adsorbed on the cation exchange group are wet-reduced with a reducing agent solution, the metal is deposited in an island shape on the resin surface, so that it is difficult to form a metal film without defects. there were. In order to improve this problem, for example, in Patent Document 3, reduction treatment of a polyimide resin in which metal ions are adsorbed on a cation exchange group is performed in a reducing agent solution adjusted to pH 1 to 6, and electroless plating is further performed. The technology is described. However, the method of Patent Document 3 requires a step of introducing a cation exchange group into the polyimide resin in addition to the electroless plating step, and has a drawback that the number of steps increases.

JP 2002-324966 A JP 2005-154880 A JP 2002-266075 A

  The methods of Patent Document 2 and Patent Document 3 are methods in which an electroless plating process is essential in order to form a metal film having no defects on the surface of the substrate. However, the electroless plating has a problem that the management of the plating solution and the treatment of the waste solution are complicated. For this reason, development of the alternative technique which can form the conductor layer excellent in the adhesiveness to the base-material surface, without using electroless plating was strongly calculated | required.

  The present invention has been made in view of the above-mentioned problems, and the object thereof is to provide a conductor layer having excellent adhesion strength with an insulating substrate and having few defects on the insulating substrate without requiring an electroless plating process. Is to form.

The method for forming the conductor layer of the present invention includes:
A method for forming a conductor layer that forms a conductor layer on an insulating substrate,
A coating film forming step of coating a coating liquid containing a polyimide precursor resin on the surface of the insulating base material and drying to form a coating film;
An immersion step of immersing the coating film in a solution containing a metal compound and impregnating a surface layer of the coating film with metal ions in the solution;
A metal film forming step of forming a metal film as the conductor layer by reducing metal ions impregnated in a surface layer of the coating film by the dipping process;
An imidization step of performing a heat treatment to imidize the polyimide precursor resin in the coating film to form a polyimide resin layer;
It has.

  In the method for forming a conductor layer of the present invention, in the coating film forming step, the coating solution may be applied in a thin line shape with a predetermined pattern on the surface of the insulating base material. In this case, the coating solution may be applied using a dispenser, or the coating solution may be applied using a droplet discharge device having a droplet discharge head that discharges micro droplets.

  Further, in the method for forming a conductor layer of the present invention, it may further comprise a surface treatment step of treating the surface of the insulating substrate with a silane coupling agent before the coating film forming step, or Prior to the coating film forming step, a surface treatment step of treating the surface of the insulating substrate with plasma may be further included.

The method for manufacturing the circuit board of the present invention includes:
A method for manufacturing a circuit board comprising an insulating base material and a conductor layer formed on the insulating base material, wherein the conductor layer is formed by the method for forming a conductor layer.

  In the present invention, the “conductor layer” formed on the insulating substrate includes a metal film formed by reduction of metal ions, and includes the metal film and an electroplating layer formed thereon. Used in both meanings. In addition, the conductor layer may have arbitrary layers other than a metal film and an electroplating layer.

  In the method for forming a conductor layer of the present invention, a coating solution containing a polyimide precursor resin is applied to the surface of an insulating substrate and dried to form a coating film, and then the surface layer of the coating film is impregnated with metal ions. A metal film is formed by reduction treatment. Since the polyimide precursor resin before imidization is easily impregnated with metal ions, it is possible to impregnate a sufficient amount of metal ions without introducing cation exchange groups on the resin surface as in Patent Document 3 above. it can. Then, by performing the reduction treatment in a state where the polyimide precursor resin is impregnated with a sufficient amount of metal ions, it is possible to easily form a dense metal film having excellent adhesion to the polyimide resin. Therefore, according to the present invention, there is an effect that a conductor layer having few defects can be formed with a small number of steps without requiring an electroless plating step or a cation exchange group introduction step.

  In addition, according to the method for manufacturing a circuit board using the method for forming a conductor layer of the present invention, it is possible to manufacture a highly reliable electronic component with excellent adhesion between the insulating base and the conductor layer at a high yield. Play.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a perspective view showing a schematic configuration of a circuit board to which a method for forming a conductor layer according to an embodiment of the present invention is applied. FIG. 2 is an explanatory view showing, in an enlarged manner, a cross section of a main part of the circuit board of FIG.

  First, a circuit board 1 to which an embodiment of the present invention is applied will be described with reference to FIGS. The circuit board 1 includes an insulating base material 3 and a patterned conductor layer 5 serving as a wiring on the insulating base material 3. As the insulating base 3, for example, an inorganic substrate such as a glass substrate, a silicon substrate, or a ceramic substrate, or a synthetic resin substrate such as polyimide resin or polyethylene terephthalate (PET) can be used.

  As shown in FIG. 2, the patterned conductor layer 5 includes a metal coating 9 formed on the insulating substrate 3 via the polyimide resin layer 7, and an electroplating layer 11 formed so as to cover the metal coating 9. have. The polyimide resin layer 7, the metal coating 9, and the electroplating layer 11 are patterned in a predetermined shape. In the present embodiment, only the metal coating 9 or the metal coating 9 and the electroplating layer 11 are referred to as “patterned conductor layer 5”. The patterned conductor layer 5 may have an arbitrary layer in addition to the above layers.

  The polyimide resin layer 7 is mainly composed of a polyimide resin that is imidized by heating and dehydrating and cyclizing a polyamic acid that is a polyimide precursor resin. The polyimide resin is preferably used because it has properties excellent in heat resistance and dimensional stability as compared with other synthetic resins such as thermosetting resins such as epoxy resins, phenol resins, and acrylic resins. The polyimide resin layer 7 in the present embodiment is formed by imidizing a polyimide precursor resin after pattern-coating a coating liquid containing a polyimide precursor resin on the insulating substrate 3. For this reason, the polyimide resin layer 7 has high adhesion to the insulating substrate 3. Such a polyimide resin layer 7 is interposed between the insulating substrate 3 and the metal coating 9 and serves as a binder.

  The metal coating 9 is a coating made of metal deposited on the surface of the polyimide precursor resin (polyimide resin layer 7) by reducing metal ions impregnated in the polyimide precursor resin. Although the metal type in this metal coating 9 is not ask | required, since high adhesiveness is obtained between the electroplating layers 11, it is preferable to use the metal seed | species different from the metal which comprises the electroplating layer 11. FIG. As the metal constituting the metal coating 9, for example, Cu, Ni, Pd, Ag, Au, Pt, Sn, Fe, Co, Cr, Rh, Ru and the like are preferable, and among these, Ni, Cu, Cr, Pd and the like are preferable. Particularly preferred.

  The electroplating layer 11 is a metal film mainly composed of, for example, Cu, Au, Ni, Co, Sn, Pd, Sn—Cu, or the like. Among these metals, Cu, Au, etc. can be preferably used.

  In the circuit board 1, the metal coating 9 is formed by impregnating the coating film 40 with metal ions and then reducing. For this reason, the adhesion between the polyimide resin layer 7 and the metal coating 9 is excellent due to the anchor effect by impregnation. Further, the electroplating layer 11 is firmly fixed to the polyimide resin layer 7 with a metal coating 9 being a metal layer interposed therebetween. Furthermore, since the polyimide resin layer 7 is formed by imidizing after applying the polyimide precursor resin to the insulating base material 3, the polyimide resin layer 7 has high adhesion to the insulating base material 3. Yes. From the above, the circuit board 1 to which the method for forming a conductor layer according to the present embodiment is applied is less likely to cause a peeling problem even when the pattern is miniaturized, and has high reliability.

[First Embodiment]
Next, a method for forming a conductor layer according to the first embodiment of the present invention will be described with reference to FIGS. The conductor layer formed in the present embodiment is a patterned conductor layer. FIG. 3 is a flowchart showing an outline of main steps in the method for forming a conductor layer according to the present embodiment. 4 to 9 are explanatory views for explaining main steps of the method for forming a conductor layer according to the present embodiment.

  As shown in FIG. 3, the method for forming a conductor layer according to the present embodiment includes steps S1 to S5 as main steps.

  In step S1, the coating liquid 20 containing the polyimide precursor resin is applied to the insulating base material 3 in a predetermined pattern using a dispenser 30 as shown in FIG. 4, and dried to form a coating film 40 (application). Film forming step). In addition, the code | symbol 40a in FIG. 4 means the coating film before drying. FIG. 5 shows a cross-sectional shape of the coating film 40 formed on the insulating substrate 3 in the coating film forming step of Step S1.

  In the present embodiment, as the coating liquid 20, a liquid containing a polyimide precursor resin before imidization is used. The polyimide precursor resin has a property of easily impregnating metal ions. As the polyimide precursor resin used in the coating solution 20, a polyamic acid obtained from the same monomer component as the polyimide resin or a polyamic acid containing a photosensitive group such as an ethylenically unsaturated hydrocarbon group in the molecule is used. . Such a polyimide precursor resin can be produced by reacting a known diamine compound and an acid anhydride in the presence of a solvent.

  Here, examples of the diamine compound used for the production of the polyimide precursor resin include 4,4′-diaminodiphenyl ether, 2′-methoxy-4,4′-diaminobenzanilide, and 1,4-bis (4-amino). Phenoxy) benzene, 1,3-bis (4-aminophenoxy) benzene, 2,2′-bis [4- (4-aminophenoxy) phenyl] propane, 2,2′-dimethyl-4,4′-diaminobiphenyl 3,3′-dihydroxy-4,4′-diaminobiphenyl, 4,4′-diaminobenzanilide and the like.

  Examples of diamine compounds other than the above include 2,2-bis- [4- (3-aminophenoxy) phenyl] propane, bis [4- (4-aminophenoxy) phenyl] sulfone, and bis [4- (3 -Aminophenoxy) phenyl] sulfone, bis [4- (4-aminophenoxy)] biphenyl, bis [4- (3-aminophenoxy) biphenyl, bis [1- (4-aminophenoxy)] biphenyl, bis [1- (3-Aminophenoxy)] biphenyl, bis [4- (4-aminophenoxy) phenyl] methane, bis [4- (3-aminophenoxy) phenyl] methane, bis [4- (4-aminophenoxy) phenyl] ether Bis [4- (3-aminophenoxy) phenyl] ether, bis [4- (4-aminophenoxy)] benzopheno Bis [4- (3-aminophenoxy)] benzophenone, bis [4,4 ′-(4-aminophenoxy)] benzanilide, bis [4,4 ′-(3-aminophenoxy)] benzanilide, 9,9 -Bis [4- (4-aminophenoxy) phenyl] fluorene, 9,9-bis [4- (3-aminophenoxy) phenyl] fluorene, 2,2-bis- [4- (4-aminophenoxy) phenyl] Hexafluoropropane, 2,2-bis- [4- (3-aminophenoxy) phenyl] hexafluoropropane, 4,4'-methylenedi-o-toluidine, 4,4'-methylenedi-2,6-xylidine, 4 4,4'-methylene-2,6-diethylaniline, 4,4'-diaminodiphenylpropane, 3,3'-diaminodiphenylpropane, 4,4'-diaminodiphenylethane, 3, 3,3'-diaminodiphenylethane, 4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane, 4,4'-diaminodiphenyl sulfide, 3,3'-diaminodiphenyl sulfide, 4,4'-diaminodiphenylsulfone 3,3′-diaminodiphenyl sulfone, 4,4′-diaminodiphenyl ether, 3,3-diaminodiphenyl ether, 3,4′-diaminodiphenyl ether, benzidine, 3,3′-diaminobiphenyl, 3,3′-dimethyl- 4,4′-diaminobiphenyl, 3,3′-dimethoxybenzidine, 4,4 ″ -diamino-p-terphenyl, 3,3 ″ -diamino-p-terphenyl, m-phenylenediamine, p-phenylene Diamine, 2,6-diaminopyridine, 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4 Aminophenoxy) benzene, 4,4 ′-[1,4-phenylenebis (1-methylethylidene)] bisaniline, 4,4 ′-[1,3-phenylenebis (1-methylethylidene)] bisaniline, bis (p -Aminocyclohexyl) methane, bis (p-β-amino-t-butylphenyl) ether, bis (p-β-methyl-δ-aminopentyl) benzene, p-bis (2-methyl-4-aminopentyl) benzene P-bis (1,1-dimethyl-5-aminopentyl) benzene, 1,5-diaminonaphthalene, 2,6-diaminonaphthalene, 2,4-bis (β-amino-t-butyl) toluene, 2, 4-diaminotoluene, m-xylene-2,5-diamine, p-xylene-2,5-diamine, m-xylylenediamine, p-xylylenediamine, 2,6-diaminopyridine, 2,5 Diaminopyridine, 2,5-diamino-1,3,4-oxadiazole, it can also be used piperazine.

  Examples of the acid anhydride used in the production of the polyimide precursor resin include pyromellitic anhydride, 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride, 3,3 ′, 4,4′- Examples thereof include diphenylsulfone tetracarboxylic dianhydride and 4,4′-oxydiphthalic anhydride. Moreover, as an acid anhydride other than the above, for example, 2,2 ′, 3,3′-, 2,3,3 ′, 4′- or 3,3 ′, 4,4′-benzophenonetetracarboxylic dianhydride 2,3 ', 3,4'-biphenyltetracarboxylic dianhydride, 2,2', 3,3'-biphenyltetracarboxylic dianhydride, 2,3 ', 3,4'-diphenyl ether tetra Preferred examples include carboxylic dianhydride and bis (2,3-dicarboxyphenyl) ether dianhydride. Also, 3,3 ", 4,4"-, 2,3,3 ", 4"-or 2,2 ", 3,3" -p-terphenyltetracarboxylic dianhydride 2,2-bis (2,3- or 3,4-dicarboxyphenyl) -propane dianhydride, bis (2,3- or 3.4-dicarboxyphenyl) methane dianhydride, bis (2, 3- or 3,4-dicarboxyphenyl) sulfone dianhydride, 1,1-bis (2,3- or 3,4-dicarboxyphenyl) ethane dianhydride, 1,2,7,8-1, , 2,6,7- or 1,2,9,10-phenanthrene-tetracarboxylic dianhydride, 2,3,6,7-anthracene tetracarboxylic dianhydride, 2,2-bis (3,4 -Dicarboxyphenyl) tetrafluoropropane dianhydride, 2,3,5,6-cyclohexane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalene Tetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 4,8-dimethyl-1,2,3,5,6,7-hexahydronaphthalene-1,2,5 , 6-tetracarboxylic dianhydride, 2,6- or 2,7-dichloronaphthalene-1,4,5,8-tetracarboxylic dianhydride, 2,3,6,7- (or 1,4 , 5,8-) tetrachloronaphthalene-1,4,5,8- (or 2,3,6,7-) tetracarboxylic dianhydride, 2,3,8,9-, 3,4,9 , 10-, 4,5,10,11- or 5,6,11,12-perylene-tetracarboxylic dianhydride, cyclopentane-1,2,3,4-tetracarboxylic dianhydride, pyrazine- 2,3,5,6-tetracarboxylic dianhydride, pyrrolidine-2,3,4,5-tetracarboxylic dianhydride, thiophene-2,3,4,5-tetracarboxylic dianhydride, 4 , 4-bis (2,3-dicarboxyphenoxy) diphenylmethane dianhydride and the like can also be used.

  Each of the diamine compound and acid anhydride may be used alone or in combination of two or more. In addition, a diamine compound or acid anhydride other than the above can be used in combination with the diamine compound and acid anhydride. In this case, the proportion of the diamine compound or acid anhydride other than the above can be 90 mol% or less, preferably 50 mol% or less. In the production of the polyimide precursor resin, by selecting the diamine compound and the type of acid anhydride and the respective molar ratios when using two or more diamine compounds or acid anhydrides, thermal expansion, adhesiveness, The glass transition point (Tg) and the like can be controlled.

  The reaction between the diamine compound and the acid anhydride is preferably performed in an organic solvent. Although it does not specifically limit as such an organic solvent, Specifically, for example, dimethyl sulfoxide, N, N-dimethylformamide, N, N-dimethylacetamide, N-methyl-2-pyrrolidone, hexamethyl phosphoramide, Examples thereof include phenol, cresol, and γ-butyrolactone, and these can be used alone or in combination. The amount of the organic solvent used is not particularly limited, but the concentration of the polyimide precursor resin (polyamic acid) solution obtained by the polymerization reaction is in the range of about 5 to 30% by weight. It is preferable to adjust and use as described above. The solution thus adjusted can be used as the coating solution 20 as it is.

  The polyimide precursor resin is preferably selected so that the polyimide resin layer 7 after imidization contains a thermoplastic polyimide resin. By using the thermoplastic polyimide resin, the polyimide resin layer 7 after imidation can be made to function as an adhesive layer that enhances the adhesion between the insulating substrate 3 and the metal coating 9.

  The viscosity of the coating solution 20 is preferably a viscosity in the range of 10 to 100,000 cps. When the viscosity of the coating solution 20 is less than 10 cps, it may be difficult to control the target line width when coating using the dispenser 30. Moreover, when the viscosity of the coating liquid 20 exceeds 100,000 cps, there is a possibility that the coating liquid 20 is clogged in the nozzle of the dispenser 30 and cannot be applied to the insulating substrate 3. Further, the viscosity of the coating solution 20 can be adjusted by the line width of the coating film 40. For example, when the line width L of the coating film 40 is in the range of 10 μm to 100 μm, the viscosity of the coating solution 20 is preferably in the range of 10 to 100 cps. When the line width L of the coating film 40 is in the range of more than 100 μm and not more than 200 μm, the viscosity of the coating solution 20 is preferably in the range of 100 to 500 cps. When the line width L of the coating film 40 is in the range of more than 200 μm and not more than 300 μm, the viscosity of the coating solution 20 is preferably in the range of 500 to 50,000 cps. When the line width L of the coating film 40 is in the range of more than 300 μm and not more than 400 μm, the viscosity of the coating solution 20 is preferably in the range of 50,000 to 70,000 cps. When the line width L of the coating film 40 is in the range of more than 400 μm and 500 μm or less, the viscosity of the coating solution 20 is preferably in the range of 70,000 to 90,000 cps. When the line width L of the coating film 40 is in the range of more than 500 μm and 600 μm or less, the viscosity of the coating solution 20 is preferably in the range of 90,000 to 100,000 cps.

  The viscosity of the polyimide precursor resin solution as the coating solution 20 can be adjusted by controlling the molecular weight of the polyimide precursor resin and the solid content concentration of the polyimide precursor resin solution. In the present embodiment, since the coating liquid 20 does not contain a metal compound (metal ion), it is not necessary to add a viscosity modifier to the coating liquid 20. Therefore, even if the wet reduction process is employed, the problem that the polyimide precursor resin is eluted by the action of the viscosity modifier and the reduction efficiency is reduced does not occur, and an efficient reduction treatment is possible.

  The weight average molecular weight of the polyimide precursor resin is preferably in the range of 10,000 to 300,000, more preferably in the range of 15,000 to 250,000, and in the range of 30,000 to 200,000. Further preferred. If the weight average molecular weight of the polyimide precursor resin is less than 10,000, the polyimide resin formed by subsequent imidization may become brittle. On the other hand, when the weight average molecular weight of the polyimide precursor resin exceeds 300,000, the viscosity of the polyimide precursor resin solution as the coating solution 20 becomes too high and handling becomes difficult. The solid content concentration of the polyimide precursor resin solution is preferably in the range of 5 to 30% by weight.

  As an optional component other than the essential components, for example, a leveling agent, an antifoaming agent, an adhesion-imparting agent, a crosslinking agent, and the like can be blended in the coating liquid 20.

  The coating solution 20 can be prepared, for example, by mixing the polyimide precursor resin and the above optional components in an arbitrary solvent such as a pyridine solvent or an imidazole solvent. In the present embodiment, a polyamic acid varnish containing polyamic acid can be used as the coating solution 20 (polyimide precursor resin solution). As the polyamic acid varnish, for example, thermoplastic polyimide varnish SPI-200N (trade name), SPI-300N (trade name), SPI-1000G (trade name) manufactured by Nippon Steel Chemical Co., Ltd., manufactured by Toray Industries, Inc. Trenice # 3000 (trade name) can be used.

  In the coating film forming step of step S1, a dispenser 30 that discharges the coating liquid 20 can be of a known configuration. As a commercial product, for example, CASTPRO II (trade name; manufactured by Sony Corporation) can be used. By using the dispenser 30, it is possible to apply the coating liquid 20 directly in a predetermined pattern even on a three-dimensional surface such as an uneven surface or a curved surface. Therefore, not only the conventional two-dimensional (planar) circuit formation but also a three-dimensional (solid) circuit formation is possible.

  When the coating film 40 is formed, the line width L of the patterned coating film 40 is preferably in the range of 10 to 400 μm, and more preferably in the range of 15 to 200 μm. Further, the line width L of the coating film 40 formed by the dispenser can be adjusted by adjusting the viscosity of the polyimide precursor resin solution, controlling the nozzle (discharge port) diameter, controlling the discharge pressure, controlling the drawing speed, or a combination thereof. The size can be adjusted. In the present embodiment, as described above, the viscosity of the coating liquid 20 is in the range of 10 to 100,000 cps, so that the discharge nozzle 30a of the dispenser 30 is prevented from being clogged and fine with a desired line width. Various patterns can be formed.

  In the coating film forming step of step S1, after the coating liquid 20 is discharged onto the insulating base 3, the coating film 40 is formed by drying. The drying is preferably performed at a temperature within the range of 50 to 150 ° C, more preferably within the range of 80 to 140 ° C, and even more preferably within the range of 100 to 120 ° C. It can be performed by heating for about 3 to 10 minutes. In this case, if the heating temperature exceeds 150 ° C., imidization of the polyimide precursor resin proceeds, and it is difficult to impregnate the metal ions in the subsequent dipping process (step S2). It is preferable to dry with.

Next, in step S2, the insulating base material 3 having the coating film 40 is immersed in a solution containing a metal compound (hereinafter referred to as “metal compound solution”) (immersion step). In the dipping process of step S2, as shown in FIG. 6, the impregnation layer 41 is formed by impregnating the metal ions in the metal compound solution into the surface layer portion of a certain depth from the surface of the coating film 40. The metal compound used in this dipping step can be used without particular limitation as long as it is a compound containing a metal species having a redox potential higher than the redox potential of the reducing agent. Examples of the metal compound include those containing metal species such as Cu, Ni, Pd, Ag, Au, Pt, Sn, Fe, Co, Cr, Rh, and Ru. Moreover, as a metal compound, the said metal salt, an organic carbonyl complex, etc. can be used. Examples of the metal salt include hydrochloride, sulfate, acetate, oxalate, and citrate. Metal salts are preferably used when the metal is Cu, Ni or Pd. Preferred specific examples of the metal _{compounds, Ni (CH 3 COO) 2} , Cu (CH 3 COO) 2, Pd (CH 3 COO) 2, NiSO 4, CuSO 4, PdSO 4, NiCO 3, CuCO 3, PdCO 3, NiCl ₂ , CuCl ₂ , PdCl ₂ , NiBr ₂ , CuBr ₂ , PdBr ₂ , Ni (NO ₃ ) ₂ , NiC ₂ O ₄ , Ni (H ₂ PO ₂ ) ₂ , Cu (NH ₄ ) ₂ Cl ₄ , CuI, List Cu (NO ₃ ) ₂ , Pd (NO ₃ ) ₂ , Ni (CH ₃ COCH ₂ COCH ₃ ) ₂ , Cu (CH ₃ COCH ₂ COCH ₃ ) ₂ , Pd (CH ₃ COCH ₂ COCH ₃ ) ₂ Can do.

  Examples of the organic carbonyl compound that forms an organic carbonyl complex with the metal include β-diketones such as acetylacetone, benzoylacetone, and dibenzoylmethane, and β-ketocarboxylic acid esters such as ethyl acetoacetate.

  In the metal compound solution used in the dipping process, the metal compound is preferably contained within a range of 30 to 300 mM, and more preferably within a range of 50 to 100 mM. If the concentration of the metal compound is less than 30 mM, it is not preferable because it takes too much time to impregnate the surface of the coating film 40 with metal ions. As a result, the patterned conductor layer 5 is deteriorated.

  In addition to the metal compound, the metal compound solution can contain components for adjusting the pH such as a buffer solution.

  In the dipping step, for example, the metal compound solution having the above concentration is adjusted to a temperature within the range of 20 to 40 ° C., and the insulating substrate 3 on which the coating film 40 is formed is dipped therein. The immersion time may be a time that allows the surface layer portion of the coating film 40 to be impregnated with the metal ions in the metal compound solution to form the impregnated layer 41, and is preferably 5 minutes to 5 hours, for example, and 5 minutes to 2 hours. More preferred. If the immersion time is shorter than 5 minutes, the coating film 40 is not sufficiently impregnated with metal ions, and the anchor effect described later cannot be sufficiently obtained. On the other hand, even if the immersion time exceeds 5 hours, the degree of impregnation of the metal ions into the coating film 40 reaches a peak, and thus further improvement in the effect cannot be desired.

  Next, in step S3, the metal ion in the impregnation layer 41 of the coating film 40 is reduced to form the metal film 9 (metal film formation step). The reduction treatment method in the metal film forming step of step S3 is not particularly limited. For example, a wet reduction method, a hydrogen reduction method, an ultraviolet irradiation reduction method, an electron beam irradiation method, a heating reduction method, an electrical reduction method, or the like. Can be adopted. The wet reduction method is a method of reducing metal ions by immersing the coating film 40 on which the impregnated layer 41 is formed in a solution containing a reducing agent (reducing agent solution). The ultraviolet irradiation reduction method is a method of reducing metal ions by irradiating the coating film 40 on which the impregnation layer 41 is formed with ultraviolet rays. The hydrogen reduction method is a method in which the coating film 40 on which the impregnation layer 41 is formed is placed in a hydrogen atmosphere and metal ions are reduced. Among these reduction treatment methods, it is preferable to employ a wet reduction method in which the unevenness of precipitation of the metal film 9 in the metal film forming step is small and the effect of forming a uniform metal film in a short time is great.

  In addition, like the above-mentioned patent document 2 (Unexamined-Japanese-Patent No. 2005-154880), in the polyimide precursor resin solution containing a palladium ion and a polyimide precursor resin, the polyamic acid which is a palladium ion and a polyimide precursor resin is used. A three-dimensional cross-linking reaction occurs between the molecules. For this reason, with the passage of time, the polyimide precursor resin solution thickens and gels, making it difficult to apply to the polyimide substrate. In order to prevent such thickening and gelation, in the technique of Patent Document 2, low molecular organic compounds such as acetylacetone and ethyl acetoacetate are added as viscosity stabilizers to the polyimide precursor resin solution. However, since the low molecular weight organic compound has a dissolving action with respect to the polyimide precursor resin, there is a problem that the polyimide precursor resin is eluted into the reducing agent solution in the wet reduction process and causes a reduction in reduction efficiency. there were. For this reason, in the method of Patent Document 2 using a polyimide precursor resin solution containing a low molecular weight organic compound, a wet reduction method with good reduction efficiency cannot be adopted, and metal ions are reduced by an ultraviolet irradiation method. Yes. On the other hand, in the method for forming a conductor layer according to the present embodiment, since the metal compound is not included in the coating liquid 20 (polyimide precursor resin solution), wet reduction can be employed.

  As a reducing agent used in the wet reduction method which is the most preferable reduction treatment method, for example, boron compounds such as sodium borohydride, potassium borohydride, dimethylamine borane and the like are preferable. These boron compounds can be used in the form of a solution (reducing agent solution) of sodium hypophosphite, formalin, hydrazines, and the like. The concentration of the boron compound in the reducing agent solution is preferably in the range of 0.005 to 0.5 mol / L, for example, and more preferably in the range of 0.01 to 0.1 mol / L. When the concentration of the boron compound in the reducing agent solution is less than 0.005 mol / L, the reduction of metal ions contained in the impregnation layer 41 of the coating film 40 may be insufficient, and when the concentration exceeds 0.1 mol / L. The polyimide precursor resin in the coating film 40 may be dissolved by the action of the boron compound.

  In the wet reduction treatment, the insulating base material 3 on which the coating film 40 is formed is placed in a reducing agent solution at a temperature in the range of 10 to 90 ° C., preferably in the range of 50 to 70 ° C., for 20 seconds to 30 seconds. Immerse in minutes, preferably 30 seconds to 10 minutes, more preferably 1 minute to 5 minutes.

  Through the metal film forming process described above, the metal ions on the surface of the coating film 40 are reduced and the metal is deposited, so that the metal film 9 covering the coating film 40 is formed as shown in FIG. This metal film 9 can be used as a nucleus of electroplating performed later.

  In the method for forming a conductor layer according to the present embodiment, the dipping process in step S2 and the metal film forming process in step S3 are repeated a plurality of times, for example, about 2 to 10 times, preferably about 2 to 5 times as necessary. be able to. Thereby, the metal coating 9 becomes denser, and sufficient conduction can be ensured in the subsequent electroplating process.

Next, in step S4, electroplating is performed using the metal coating 9 as a core to form an electroplating layer 11 (electroplating step). As shown in FIG. 8, an electroplating layer 11 is formed by electroplating so as to cover the metal film 9. In addition, the electroplating process of this step S4 is an arbitrary process. The electroplating is performed, for example, in a plating solution having a composition containing sulfuric acid, copper sulfate, hydrochloric acid, and a brightener [for example, McCuispec (trade name) manufactured by Nihon McDermitt as a commercial product], and the metal coating 9 of the insulating base 3. Can be used as a cathode and a metal such as Cu can be used as an anode. Current density in electroplating, for example, is preferably in the range of 1~3.5A / dm ^2. As the anode for electroplating, for example, metals such as Ni and Co can be used in addition to Cu.

  Next, in step S5, the insulating base material 3 having the coating film 40 and the metal coating 9 is heat-treated to imidize the polyimide precursor resin in the coating film 40 (imidization process). The polyamic acid in the coating film 40 is dehydrated, cyclized and imidized by heat treatment, whereby the polyimide resin layer 7 having excellent adhesion to the insulating substrate 3 is formed as shown in FIG. The imidization can be preferably performed in an inert gas atmosphere such as nitrogen using a heat treatment apparatus capable of heating the coating film 40 to a required temperature. The heat treatment can be performed for 1 to 60 minutes under a temperature condition within a range of 150 to 400 ° C., for example. If the heat treatment temperature is less than 150 ° C., imidization does not proceed sufficiently, and if the heat treatment temperature exceeds 400 ° C., there is a risk of causing thermal decomposition of the polyimide resin.

  As described above, the circuit board 1 in which the patterned conductor layer 5 serving as the metal wiring is formed on the surface of the insulating base 3 can be manufactured. The circuit board 1 can be suitably used for applications such as a hard printed board, a flexible printed board, a TAB (Tape Automated Bonding) material, a CSP (Chip Size Package) material, and a COG (Chip on Glass) material.

  In the present embodiment, a coating film forming step (step S1) for forming the coating film 40 using the coating liquid 20 containing no metal compound, and the insulating base material 3 having the coating film 40 are immersed in the metal compound solution. An immersion process (step S2) for forming the impregnation layer 41 on the surface layer of the coating film 40, and a metal film formation process (step S3) for forming the metal film 9 by reducing metal ions contained in the impregnation layer 41. The configuration was provided. By using the coating solution 20 that does not contain a metal compound in this way, the problem of an increase in the viscosity of the coating solution 20 does not occur, and the handling of the coating solution 20 becomes easy. That is, since the coating liquid 20 used in the present embodiment does not contain a metal compound, there is no problem of thickening / gelling due to cross-linking between metal ions and polyamic acid. Therefore, even if the dispenser 30 is used for application of the application liquid 20, clogging of the nozzle hardly occurs and application is easy. In addition, since it is not necessary to add a viscosity modifier to the coating solution 20, there is a problem of elution of the polyimide precursor resin by the viscosity modifier even if an efficient wet reduction method is employed for the metal ion reduction treatment. Don't worry. Furthermore, since the polyimide precursor resin constituting the coating film 40 has the property of being easily impregnated with metal ions, the coating film 40 is formed on the insulating base 3 and then subjected to immersion treatment and reduction treatment. It is possible to easily form a dense metal film 9 with a sufficient thickness on the surface of the film 40, and sufficient electrical conduction can be achieved without electroless plating or introduction of a cation exchange group. . The densely formed metal film 9 can be used as an electroplating nucleus (base) as it is. Therefore, in the method for forming the patterned conductor layer according to the present embodiment, the electroless plating process, which is essential in the prior art, is unnecessary, and the patterning can be performed without causing the problem of plating solution management and waste liquid treatment. The conductor layer 5 can be formed.

  Further, in this embodiment, the coating liquid 20 containing the polyimide precursor resin is applied onto the insulating base material 3 to form the coating film 40 and then imidized to form the polyimide layer 7. High adhesion is obtained between the material 3 and the polyimide resin layer 7. The metal film 9 obtained by impregnating the coating film 40 made of the polyimide precursor resin with metal ions and then reducing the metal film 9 has an anchor effect on the polyimide resin layer 7. Due to this anchor effect, the adhesion between the polyimide resin layer 7 and the metal coating 9 is enhanced. In addition, since the polyimide resin used in the present embodiment is easier to control the molecular orientation than other synthetic resins, the thermal expansion coefficient of the polyimide resin layer 7 is kept low, and the metal coating 9 and the electroplating used as the wiring It becomes possible to approach the thermal linear expansion coefficient of the metal constituting the layer 11. From the above, in this embodiment, the patterned conductor layer 5 having excellent adhesion to the insulating base material 3 can be formed.

  In the present embodiment, the coating liquid 20 is directly applied to the insulating substrate 3 in a predetermined pattern using the dispenser 30, so that a photolithography process or an etching process is performed in the formation process of the patterned conductor layer 5. Can be omitted. Furthermore, by using the dispenser 30 for applying the coating liquid 20, the patterned conductor layer 5 can be easily formed even on a three-dimensional surface such as an uneven surface or a curved surface of the insulating substrate 3, for example. Therefore, in the present embodiment, not only a flat plate but also a three-dimensional circuit board 1 can be manufactured with a small number of steps.

  According to the method for manufacturing a circuit board using the method for forming a conductor layer according to the present embodiment, it is possible to manufacture a highly reliable electronic component with high adhesion between the insulating base and the conductor layer and high reliability. In the present embodiment, since a conductive paste containing conductive metal fine particles is not used, a sintering process is unnecessary, and conduction failure of the patterned conductor layer 5 is unlikely to occur.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 10 is a flowchart showing an outline of the procedure of the method for forming a conductor layer according to the present embodiment. The method for forming a conductor layer according to the present embodiment includes steps S11 to S16 shown in FIG. In the present embodiment, the surface treatment process in step S11 for modifying the surface of the insulating substrate 3 before the coating film forming process in step S12 corresponding to the coating film forming process in step S1 in the first embodiment. It has. In addition, since each process to step S12-step S16 in this Embodiment is the same as each process to step S1-step S5 of 1st Embodiment, description is abbreviate | omitted.

  In the present embodiment, in the surface treatment process of step S11, it is preferable to select the content of the surface modification according to the material of the insulating base material 3. When the insulating base material 3 is comprised with inorganic materials, such as a glass substrate and a ceramic substrate, it is preferable to surface-treat the surface of the insulating base material 3 with a silane coupling agent. In this case, the surface treatment can be performed, for example, by immersing the insulating substrate 3 in a solution of a silane coupling agent. By the surface treatment with the silane coupling agent, the surface of the insulating base material 3 made of an inorganic material is hydrophobized, the flow of the liquid after the coating liquid 20 is applied can be suppressed, and the spread of the line width can be suppressed. In addition, the adhesion between the coating film 40 and the insulating substrate 3 can be improved by surface treatment with a silane coupling agent. Therefore, the accuracy of the pattern formed by the coating film 40 can be maintained, and the occurrence of defects in which the patterned conductor layer 5 is peeled off from the insulating base 3 can be reduced. The surface treatment on the insulating substrate 3 is preferably performed such that the contact angle with water is within a range of 20 to 110 °, for example, and more preferably within a range of 30 to 100 °. Good. In this case, if the contact angle with water is less than 20 °, it becomes difficult to suppress the flow of the liquid after the coating liquid 20 is applied, and if it exceeds 110 °, the coating film 40 and the insulating substrate 3 are in close contact with each other. May be reduced.

  Examples of the silane coupling agent used for the surface treatment include 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropyltriethoxysilane, and 3- (2-aminoethyl). Aminopropyltrimethoxysilane, 3- (2-aminoethyl) aminopropylmethyldiethoxysilane, 3- (2-aminoethyl) aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethyl- Butylidene) propylamine, N-phenyl-3-aminopropyltrimethoxysilane, N- (vinylbenzyl) -2-aminoethyl-3-aminopropyltrimethoxysilane hydrochloride, 3-ureidopropyltriethoxysilane, 3- Mercaptopropylmethyldimethoxysilane, 3-methyl Captopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 2- (3,4 epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxytriethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxy Examples thereof include silane and 3-acryloxypropyltriethoxysilane.

  Moreover, when the insulating base material 3 is comprised with synthetic resin materials, such as a polyimide substrate and a PET (polyethylene terephthalate) board | substrate, it is preferable to surface-treat the surface of the insulating base material 3 with plasma. By this surface treatment with plasma, the surface of the insulating substrate 3 can be roughened or the chemical structure of the surface can be changed. Thereby, the wettability of the surface of the insulating substrate 3 is improved, the affinity with the coating liquid 20 is increased, and the coating liquid 20 can be stably held in a predetermined shape on the surface. Therefore, the accuracy of the pattern formed by the coating film 40 can be maintained.

  As the plasma, for example, an atmospheric pressure type plasma processing apparatus is used, and plasma of argon, helium, nitrogen, or a mixed gas thereof is generated in a vacuum processing chamber. In this case, it is preferable that the processing pressure is in the range of 5000 to 200000 Pa, the processing temperature is in the range of 10 to 40 ° C., and the high frequency (or microwave) output is in the range of 50 to 400 W.

  In addition, when the material of the insulating base material 3 is a polyimide resin, it is also effective to hydrolyze the polyimide resin on the surface of the insulating base material 3 by alkali treatment as a means for improving the adhesion between the coating film 40 and the insulating base material 3. It is. Here, examples of the alkali include alkali metal hydroxides such as LiOH, KOH, and NaOH, and preferably one or more selected from KOH or NaOH can be used.

  As described above, by performing the surface treatment process of step S11, the flow of the liquid after the coating liquid 20 is applied can be suppressed, and the spread of the line width can be suppressed. Moreover, the adhesiveness of the coating film 40 and the insulating base material 3 can also be improved by surface treatment. Therefore, while maintaining the pattern accuracy of the patterned conductor layer 5, it is possible to reduce the occurrence of defects such as peeling of the patterned conductor layer 5 due to a decrease in the adhesive strength between the insulating base material 3 and the polyimide resin layer 7. it can. Other operations and effects in the present embodiment are the same as those in the first embodiment.

[Third Embodiment]
Next, a third embodiment of the present invention will be described with reference to FIG. 11 and FIG. FIG. 11 is a flowchart showing an outline of the procedure of the method for forming a conductor layer according to the present embodiment. The method for forming a conductor layer according to the present embodiment includes steps S21 to S25 shown in FIG. In the coating film forming process in step S1 in the first embodiment, the coating liquid 20 is applied using the dispenser 30, but in the present embodiment, in the coating film forming process in step S21, fine droplets are ejected. The droplet discharge device 50 is used. In addition, since each process to step S22-step S25 in this Embodiment is the same as each process to step S2-step S5 of 1st Embodiment, description is abbreviate | omitted.

  In the present embodiment, as shown in FIG. 12A, the coating liquid 20 is applied in a predetermined pattern on the insulating base 3 using a droplet discharge device 50. The droplet discharge device 50 includes a droplet discharge head 52 that can move relative to the insulating substrate 3 in the XY directions. The droplet discharge head 52 includes a discharge mechanism (not shown) using an ink jet printer technique. As shown in FIG. 12B, the coating liquid 20 is made into fine droplets toward the insulating substrate 3. Discharge. That is, the droplet discharge head 52 includes, for example, a large number of fine nozzle holes 52a, and a pressure generating chamber (not shown) configured to be able to increase and decrease the internal volume by communicating with the nozzle holes 52a and contracting and expanding the piezo elements. And. Then, the piezoelectric element is driven by an electric drive signal from a control unit (not shown) to change the volume of the pressure generating chamber, and the application liquid 20 is discharged from each nozzle hole 52a using the increase in internal pressure generated at that time. It is configured such that it can be ejected toward the insulating substrate 3 as a fine droplet of about several picoliters to several microliters. As the droplet discharge head 52, it is possible to use a thermal type instead of the piezo type.

  As the coating liquid 20, a liquid having a composition almost similar to that of the coating liquid 20 in the first embodiment can be used. However, the viscosity of the coating liquid 20 when using the droplet discharge device 50 is preferably in the range of 10 to 20 cps. If the viscosity of the coating solution 20 is less than 10 cps, it may be difficult to control the target line width. On the other hand, if the viscosity of the coating liquid 20 exceeds 20 cps, the coating liquid 20 may be clogged in the nozzle hole 52a, making it impossible to apply. As in the first embodiment, the viscosity of the polyimide precursor resin solution as the coating solution 20 can be adjusted by controlling the molecular weight of the polyimide precursor resin and the solid content concentration of the polyimide precursor resin solution. . The molecular weight of the polyimide precursor resin used in the present embodiment, the solid content concentration of the polyimide precursor resin solution, the preparation method, and the like are the same as those in the first embodiment.

  When the coating film 40 is formed using the droplet discharge device 50, the line width L of the patterned coating film 40 is preferably in the range of 10 to 400 μm, and more preferably in the range of 15 to 200 μm. The line width L of the coating film 40 formed by using the droplet discharge head 52 of the droplet discharge device 50 is adjusted for the viscosity of the polyimide precursor resin solution, the control of the nozzle (discharge port) diameter, and the discharge pressure. It can be adjusted to a desired size by controlling the drawing, controlling the drawing speed, or a combination thereof.

  In the present embodiment, as described above, the viscosity of the coating liquid 20 is in the range of 10 to 20 cps, so that the pressure generation chamber (not shown) inside the droplet discharge head 52 of the droplet discharge device 50 is omitted. A fine pattern with a desired line width can be formed while preventing clogging in the nozzle holes 52a.

  After the coating liquid 20 is discharged onto the insulating substrate 3 from the droplet discharge head 52, it is dried. Drying can be performed under the same conditions as in step S1 in the first embodiment. Thus, the coating film 40 can be formed on the insulating base material 3 with a predetermined pattern.

  Other operations and effects in the present embodiment are the same as those in the first embodiment. In the present embodiment using the droplet discharge device 50, it is also possible to provide a surface treatment step prior to the coating film forming step, as in the second embodiment.

  Next, although an Example is given and this invention is demonstrated further more concretely, this invention is not restrict | limited by these Examples.

[Reference Example 1]
70 ml of N-methyl-2-pyrrolidinone (hereinafter abbreviated as “NMP”), 5.45 g of pyromellitic dianhydride (hereinafter abbreviated as “PMDA”) and 4,4′-diaminodiphenyl ether (hereinafter referred to as “ODA”). ”) Was added, and the mixture was stirred at room temperature for 4 hours to prepare a polyimide precursor varnish A. The viscosity of this solution was 665 cps as measured with an E-type viscometer.

[Reference Example 2]
To NMP 105 ml, 7.36 g of 3,3 ′, 4,4′-biphenyltetracarboxylic dianhydride (hereinafter abbreviated as “BPDA”) and 2,2-bis [4- (4-aminophenoxy) phenyl] propane (Hereinafter abbreviated as “BAPP”) 10.26 g was added and stirred at room temperature for 4 hours to prepare a polyimide precursor varnish B. The viscosity of this solution was 660 cps as measured with an E-type viscometer.

[Reference Example 3]
To 36 ml of NMP, 7.36 g of BPDA and 10.26 g of BAPP were added and stirred at room temperature for 4 hours to prepare polyimide precursor varnish C. The viscosity of this solution was 15 cps as measured with an E-type viscometer.

[Example 1]
A test piece 12.5 cm × 12.5 cm (thickness 0.7 mm) of alkali-free glass (Asahi Glass Co., Ltd. AN-100) was treated with a 5N sodium hydroxide aqueous solution at 50 ° C. for 5 minutes. Next, the glass substrate of the test piece was washed with pure water and dried, and then immersed in a 1 wt% aqueous solution of 3-aminopropyltrimethoxysilane (hereinafter abbreviated as “γ-APS”). The glass substrate was taken out from the γ-APS aqueous solution, dried, and heated at 150 ° C. for 5 minutes. On the glass substrate, the polyimide precursor varnish A was drawn to form a straight line having a width of about 200 μm using a dispenser (CASTPRO II (trade name) manufactured by Sony Corporation; hereinafter the same), and then 125 ° C. For 10 minutes. The thickness of the coating film formed by drawing and drying was 2 μm.

  Next, the glass substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the glass substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer, thereby forming a nickel layer as a metal film serving as a base for electrolytic copper plating.

Further, the nickel layer of the glass substrate was electroplated at a current density of 2.5 A / dm ² in an electrolytic copper plating bath to form a copper wiring layer having a copper film thickness of 20 μm.

  The obtained copper wiring formed glass substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Then, the copper wiring formation glass substrate was cooled to normal temperature in nitrogen atmosphere. This copper wiring formation glass substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the glass substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

[Example 2]
A test piece 12.5 cm × 12.5 cm (thickness 0.7 mm) of alkali-free glass (Asahi Glass Co., Ltd. AN-100) was treated with a 5N sodium hydroxide aqueous solution at 50 ° C. for 5 minutes. Next, the glass substrate of the test piece was washed with pure water and dried, and then immersed in a 1% by weight γ-APS aqueous solution. The glass substrate was taken out from the γ-APS aqueous solution, dried, and heated at 150 ° C. for 5 minutes. On this glass substrate, the polyimide precursor varnish B was drawn using a dispenser so as to be a straight line having a width of about 200 μm, and then dried at 125 ° C. for 10 minutes. The thickness of the coating film formed by drawing and drying was 2 μm.

  Next, the glass substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the glass substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer to form a nickel layer as a metal film serving as a base for electrolytic copper plating.

Further, the nickel layer of the glass substrate was electroplated at a current density of 2.5 A / dm ² in an electrolytic copper plating bath to form a copper wiring layer having a copper film thickness of 20 μm.

  The obtained copper wiring formed glass substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Then, the copper wiring formation glass substrate was cooled to normal temperature in nitrogen atmosphere. This copper wiring formation glass substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the glass substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

[Example 3]
As a polyimide substrate, a test piece 10 cm × 10 cm (thickness 25 μm) of a polyimide film “Kapton EN” (trade name) manufactured by Toray DuPont Co., Ltd. was prepared. The polyimide precursor varnish A was drawn on the polyimide substrate using a dispenser so as to be a straight line having a width of about 200 μm, and then dried at 125 ° C. for 10 minutes. The thickness of the coating film formed by drawing and drying was 2 μm.

  Next, the polyimide substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the polyimide substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer, thereby forming a nickel layer as a metal film serving as a base for electrolytic copper plating.

Furthermore, the nickel layer of the polyimide substrate was electroplated at a current density of 3.5 A / dm ^{2 in} an electrocopper plating bath to form a copper wiring layer having a copper film thickness of 20 μm.

  The obtained copper wiring-formed polyimide substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Thereafter, the copper wiring-formed polyimide substrate was cooled to room temperature in a nitrogen atmosphere. This copper wiring formation polyimide substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the polyimide substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

[Example 4]
As a polyimide substrate, a test piece 10 cm × 10 cm (thickness 25 μm) of a polyimide film “Kapton EN” (trade name) manufactured by Toray DuPont Co., Ltd. was prepared. The polyimide precursor varnish B was drawn on the polyimide substrate using a dispenser so as to form a straight line having a width of about 200 μm, and then dried at 125 ° C. for 10 minutes. The thickness of the coating film formed by drawing and drying was 2 μm.

  Next, the polyimide substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the polyimide substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer, thereby forming a nickel layer as a metal film serving as a base for electrolytic copper plating.

Furthermore, the nickel layer of the polyimide substrate was electroplated at a current density of 3.5 A / dm ^{2 in} an electrocopper plating bath to form a copper wiring layer having a copper film thickness of 20 μm.

  The obtained copper wiring-formed polyimide substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Thereafter, the copper wiring-formed polyimide substrate was cooled to room temperature in a nitrogen atmosphere. This copper wiring formation polyimide substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the polyimide substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

[Example 5]
A test piece 12.5 cm × 12.5 cm (thickness 0.7 mm) of alkali-free glass (Asahi Glass Co., Ltd. AN-100) was treated with a 5N sodium hydroxide aqueous solution at 50 ° C. for 5 minutes. Next, the glass substrate of the test piece was washed with pure water and dried, and then immersed in a 1% by weight γ-APS aqueous solution. The glass substrate was taken out from the γ-APS aqueous solution, dried, and heated at 150 ° C. for 5 minutes. On this glass substrate, the said polyimide precursor varnish A was apply | coated uniformly, and it dried for 30 minutes at 130 degreeC. The thickness of the coating film formed by coating and drying was 2 μm.

  Next, the glass substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the glass substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer, thereby forming a nickel layer as a metal film serving as a base for electrolytic copper plating.

Further, the nickel layer of the glass substrate was electroplated at a current density of 2.5 A / dm ² in an electrolytic copper plating bath to form a copper plating layer having a copper film thickness of 20 μm.

  The obtained copper plating formed glass substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Thereafter, the copper plating glass substrate was cooled to room temperature in a nitrogen atmosphere.

  After laminating a dry film resist on the copper plating layer of this copper plating formed glass substrate, it was exposed to ultraviolet rays through a photomask, developed, and 50 μm pitch {wiring width / wiring spacing (L / S) = 20 μm / 30 μm} The resist pattern was formed. The copper plating layer of the formed wiring space part was removed by etching, and the subsequent polyimide resin layer was removed by etching to obtain a copper wiring-formed glass substrate. This copper wiring formation glass substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the glass substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

[Example 6]
A test piece 12.5 cm × 12.5 cm (thickness 0.7 mm) of non-alkali glass (Asahi Glass Co., Ltd. AN-100) was treated with a 5N sodium hydroxide aqueous solution at 50 ° C. for 5 minutes. Next, the glass substrate of the test piece was washed with pure water and dried, and then immersed in a 1% by weight γ-APS aqueous solution. The glass substrate was taken out from the γ-APS aqueous solution, dried, and heated at 150 ° C. for 5 minutes. As a droplet discharge device, an ink tank cartridge of a commercially available inkjet printer was prepared by filling the polyimide precursor varnish C described above. And with this inkjet printer, the polyimide precursor varnish C was discharged on the said glass substrate, and it drawn on the straight line about 50 micrometers wide. Thereafter, the coating solution on the glass substrate was dried at a temperature of 130 ° C. for 10 minutes. The thickness of the coating film formed by drawing and drying was 0.5 μm.

  Next, the glass substrate was immersed in a 500 mM nickel acetate aqueous solution for 60 minutes, and the surface layer of the coating film was impregnated with nickel ions to form an impregnated layer. Thereafter, the polyimide substrate was further immersed in a 100 mM dimethylamine borane aqueous solution at 50 ° C. for 3 minutes to reduce nickel ions in the impregnated layer, thereby forming a nickel layer as a metal film serving as a base for electrolytic copper plating.

Further, the nickel layer of the glass substrate was electroplated at a current density of 2.5 A / dm ² in an electrolytic copper plating bath to form a copper wiring layer having a copper film thickness of 20 μm.

  The obtained copper wiring formed glass substrate was heated to 300 ° C. in a nitrogen atmosphere, and the polyimide precursor resin constituting the coating film was imidized at the same temperature for 5 minutes to form a polyimide resin layer. Then, the copper wiring formation glass substrate was cooled to normal temperature in nitrogen atmosphere. This copper wiring formation glass substrate was excellent in the adhesiveness of a polyimide resin layer and a nickel layer, and the copper wiring layer was firmly fixed to the glass substrate through these polyimide resin layers and nickel layers. Also, the nickel layer and the copper wiring layer formed using this as a base had no defects and had excellent conduction performance.

  In addition, this invention is not limited to said each embodiment, A various change is possible. For example, in the first to third embodiments, the imidization process is performed after the electroplating process, but the imidization process is performed before the electroplating process (after the metal film forming process). You can also.

  Moreover, in the said 1st-3rd embodiment, it is also possible to provide the water washing process (washing process) by a pure water, ion-exchange water, etc. after an immersion process.

  Furthermore, in the first to third embodiments, in the coating film forming step, the coating liquid is directly applied to the insulating base material in a predetermined pattern using a droplet discharge device having a dispenser or a droplet discharge head. Then, a patterned coating film was formed. However, as illustrated in Example 5 above, in the coating film formation step, a coating film is formed by applying a coating solution over the entire surface of the insulating substrate (so-called “solid coating”), and after electroplating, A conductor layer may be processed into a predetermined pattern by providing a lithography process and a chemical etching process.

  In addition, the method for forming a conductor layer of the present invention is excellent in adhesion to the surface of an insulating base material and has few defects other than the purpose of forming a patterned conductor layer used for a circuit board or the like. It can be widely used for the purpose of forming a conductor layer.

It is explanatory drawing which shows the structure of the circuit board to which the formation method of the conductor layer which concerns on embodiment of this invention is applied. It is sectional drawing which expands and shows the principal part of the circuit board shown in FIG. It is a flowchart which shows the outline | summary of the procedure of the formation method of the conductor layer which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating the coating film formation process in the formation method of the conductor layer which concerns on the 1st Embodiment of this invention. It is explanatory drawing for demonstrating the state of the coating film after a coating film formation process. It is explanatory drawing for demonstrating the state of the coating film after an immersion process. It is explanatory drawing for demonstrating the state of the patterned conductor layer after a reduction | restoration process. It is explanatory drawing for demonstrating the state of the patterned conductor layer after an electroplating process. It is explanatory drawing for demonstrating the state of the patterned conductor layer after an imidation process. It is a flowchart which shows the outline | summary of the procedure of the formation method of the conductor layer which concerns on the 2nd Embodiment of this invention. It is a flowchart which shows the outline | summary of the procedure of the formation method of the conductor layer which concerns on the 3rd Embodiment of this invention. It is explanatory drawing for demonstrating the coating film formation process in the formation method of the conductor layer which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Circuit board, 3 ... Insulation base material, 5 ... Patterned conductor layer, 7 ... Polyimide resin layer, 9 ... Metal coating, 11 ... Electroplating layer, 20 ... Coating liquid, 30 ... Dispenser, 40 ... Coating film, 50 ... Droplet ejection device.

Claims (7)

A method for forming a conductor layer that forms a conductor layer on an insulating substrate,
A coating film forming step of coating a coating liquid containing a polyimide precursor resin on the surface of the insulating base material and drying to form a coating film;
An immersion step of immersing the coating film in a solution containing a metal compound and impregnating a surface layer of the coating film with metal ions in the solution;
A metal film forming step of forming a metal film as the conductor layer by reducing metal ions impregnated in a surface layer of the coating film by the dipping process;
An imidization step of performing a heat treatment to imidize the polyimide precursor resin in the coating film to form a polyimide resin layer;
A method for forming a conductor layer, comprising:   2. The method for forming a conductor layer according to claim 1, wherein, in the coating film forming step, the coating liquid is applied in a thin line shape with a predetermined pattern on the surface of the insulating base material.   The method for forming a conductor layer according to claim 2, wherein the coating liquid is applied using a dispenser.   The method for forming a conductor layer according to claim 2, wherein the coating liquid is applied using a droplet discharge device having a droplet discharge head for discharging fine droplets.   The conductor layer formation according to any one of claims 1 to 4, further comprising a surface treatment step of treating the surface of the insulating substrate with a silane coupling agent before the coating film forming step. Method.   The method for forming a conductor layer according to any one of claims 1 to 4, further comprising a surface treatment step of treating the surface of the insulating base with plasma before the coating film forming step. A method of manufacturing a circuit board comprising an insulating substrate and a conductor layer formed on the insulating substrate,
A method for manufacturing a circuit board, wherein the conductor layer is formed by the method for forming a conductor layer according to claim 1.

Images