JP6466110B2 - Printed wiring board substrate, printed wiring board, and printed wiring board manufacturing method - Google Patents

Description

  The present invention relates to a printed wiring board substrate, a printed wiring board, and a method for manufacturing a printed wiring board substrate.

  In recent years, with the miniaturization and high performance of electronic devices, there is a demand for higher density of printed wiring boards. As a printed wiring board substrate that satisfies such a demand for higher density, a printed wiring board substrate having a reduced conductive layer is required.

  In response to such a demand, a printed wiring board substrate in which a copper thin layer is laminated on a heat-resistant insulating base film without an adhesive layer has been proposed (see Japanese Patent No. 3570802). In this conventional printed wiring board substrate, a copper thin film layer (first conductive layer) having a thickness of 0.25 to 0.30 μm is formed on both surfaces of a heat-resistant insulating base film by sputtering, and electroplating is performed thereon. The copper thick film layer (second conductive layer) is formed using the method.

Japanese Patent No. 3570802

  The conventional printed wiring board substrate can be said to be a substrate that meets the demand for high-density printed wiring in that the conductive layer can be made thin. However, since the above-mentioned conventional printed wiring board substrate forms the first conductive layer using the sputtering method in order to bring the conductive layer into close contact with the base film, it requires a vacuum facility, and the construction, maintenance and operation of the facility. Etc., the cost becomes high. In addition, all of supply of the base film to be used, formation of the conductive layer, storage of the base film, etc. must be handled in a vacuum. Further, in terms of equipment, there is a limit to increasing the size of the substrate.

  This invention is made | formed based on the above situations, and provides the manufacturing method of the printed wiring board board | substrate which can fully thin a conductive layer at low cost, a printed wiring board, and a printed wiring board board | substrate. Objective.

  As a result of intensive studies to solve the above-mentioned problems, the inventors conducted electroless plating when the surface of the conductive layer formed by applying conductive ink on the base film of the printed wiring board substrate was subjected to electroless plating. When the derived metal (nickel, palladium, etc.) exists in the base film and the conductive layer, and the amount of the metal derived from the electroless plating near the interface between the base film and the conductive layer increases, the base film and the conductive layer It has been found that there is a tendency for the adhesion between the two to increase. From this, the inventors have found that the conductive layer can be brought into close contact with the base film without using vacuum equipment.

  A printed wiring board substrate according to one embodiment of the present invention devised based on this knowledge is laminated on at least one surface of the base film by applying an insulating base film and a conductive ink containing metal particles. A first conductive layer and a second conductive layer laminated on a surface opposite to the base film of the first conductive layer by electroless plating, and the first conductive layer, the second conductive layer, and the base film A printed wiring board in which nickel is present and the amount of nickel in the near-interface layer 500 nm or less from the interface between the first conductive layer and the base film is 1% by mass or more as determined by EDX (energy dispersive X-ray spectroscopy) analysis Substrate.

  A printed wiring board according to another aspect of the present invention made to solve the above problems is a printed wiring board having a conductive pattern, and the conductive pattern is a first conductive layer of the printed wiring board substrate. And a printed wiring board formed on the second conductive layer by using a subtractive method or a semi-additive method.

  In another aspect of the present invention, a method for manufacturing a printed wiring board substrate according to an aspect of the present invention is provided to solve the above-described problems by using a conductive ink containing metal particles on at least one surface of an insulating base film. Forming a first conductive layer by coating and heating; and forming a second conductive layer on a surface of the first conductive layer opposite to the base film by electroless plating using a plating solution containing nickel. And nickel is present in the first conductive layer, the second conductive layer, and the base film, and the amount of nickel in the near-interface layer 500 nm or less from the interface between the first conductive layer and the base film is 1 mass as determined by EDX analysis. % Of the printed wiring board substrate manufacturing method.

  The printed wiring board substrate, printed wiring board, and printed wiring board manufacturing method of the present invention can sufficiently reduce the conductive layer at low cost.

It is a typical perspective view of the board | substrate for printed wiring boards which concerns on one Embodiment of this invention. It is a typical fragmentary sectional view of the board | substrate for printed wiring boards of FIG. It is a typical fragmentary sectional view explaining the manufacturing method of the board | substrate for printed wiring boards of FIG. It is a typical fragmentary sectional view explaining the process following FIG. 3A of the manufacturing method of the board | substrate for printed wiring boards of FIG. It is a typical fragmentary sectional view explaining the manufacturing method of the printed wiring board using the board | substrate for printed wiring boards of FIG. It is a typical fragmentary sectional view explaining the next process of Drawing 4A of a manufacturing method of a printed wiring board using a substrate for printed wiring boards of Drawing 1. It is a typical fragmentary sectional view explaining the next process of Drawing 4B of a manufacturing method of a printed wiring board using a substrate for printed wiring boards of Drawing 1. It is a typical fragmentary sectional view explaining the process following FIG. 4C of the manufacturing method of the printed wiring board using the board | substrate for printed wiring boards of FIG.

[Description of Embodiment of the Present Invention]
A printed wiring board substrate according to an aspect of the present invention includes an insulating base film, a first conductive layer laminated on at least one surface of the base film by applying a conductive ink containing metal particles, A second conductive layer laminated on the surface opposite to the base film of the first conductive layer by electroless plating, nickel is present in the first conductive layer, the second conductive layer, and the base film, 1 is a printed wiring board substrate in which the amount of nickel in an interface vicinity layer of 500 nm or less from the interface between one conductive layer and a base film is 1% by mass or more as determined by EDX (energy dispersive X-ray spectroscopy) analysis.

  In the printed wiring board substrate, a first conductive layer is laminated on at least one surface of a base film by applying a conductive ink containing metal particles, and an electroless surface of the first conductive layer is opposite to the base film. Since the second conductive layer is laminated by plating, expensive vacuum equipment necessary for physical vapor deposition such as sputtering is not required. Therefore, the size of the printed wiring board substrate is not limited by the vacuum equipment. In addition, the printed wiring board substrate includes a base film and a first conductive layer without providing an adhesive layer due to the presence of a predetermined amount or more of nickel in the layer near the interface between the base film and the first conductive layer. A large adhesion can be obtained between them. Although this reason is not certain, it is thought that the residual stress of the base film and the first conductive layer is reduced due to the presence of nickel, and as a result, the adhesion between the base film and the first conductive layer is improved. . Moreover, since the base film is laminated | stacked on the 1st conductive layer without using the adhesive bond layer for the said board | substrate for printed wiring boards, a conductive layer can be formed thinly enough. Further, the printed wiring board substrate is not limited by the material of the base film by laminating the first conductive layer on at least one surface of the base film by applying conductive ink containing metal particles. A printed wiring board substrate using various base films can be provided. The second conductive layer may be further electroplated on one surface laminated by electroless plating. When the average thickness of the first conductive layer is less than 500 nm, the second conductive layer is not included in the interface vicinity layer.

  It is preferable that the mass ratio of nickel in the interface vicinity layer is larger than the mass ratio of nickel in the A layer of 500 nm or less from the interface between the second conductive layer and the first conductive layer. As described above, by making the mass ratio of nickel in the interface vicinity layer larger than the mass ratio of nickel in the A layer of the second conductive layer, the first conductivity that greatly affects the separation between the first conductive layer and the base film. Since the residual stress of a layer and a base film is reduced more, it is thought that the adhesive force between a base film and a 1st conductive layer improves more. In addition, when the average thickness of a 2nd conductive layer is 500 nm or less, the said A layer shall represent the 2nd conductive layer whole.

  When palladium is present in the first conductive layer, the second conductive layer, and the base film, the mass ratio of palladium in the B layer of 1 μm or less from the interface with the first conductive layer of the base film is that of the second conductive layer. It is preferable that it is larger than the mass ratio of palladium of A layer of 500 nm or less from the interface with the first conductive layer. In this way, by making the mass ratio of palladium in the B layer of the base film larger than the mass ratio of palladium in the A layer of the second conductive layer, plating deposition at the interface between the base film and the first conductive layer is more dense. Thus, the adhesion between the base film and the first conductive layer is further improved. In addition, when the average thickness of a base film is 1 micrometer or less, the said B layer shall represent the whole base film.

  The electroless plating may be copper plating. Thus, by using electroless plating by copper plating, the second conductive layer with lower stress can be formed by the action of nickel contained in the copper plating solution.

  The average particle diameter of the metal particles is preferably 1 nm to 500 nm. As described above, the first conductive layer is laminated on the surface of the base film by applying the conductive ink containing metal particles having an average particle diameter within the above range. A dense and uniform first conductive layer is stably formed. Thereby, the 2nd conductive layer by electroless plating can be formed uniformly. Here, the “average particle diameter” means that represented by the center diameter D50 of the particle size distribution in the dispersion. The average particle size can be measured with a particle size distribution measuring device (for example, Microtrack particle size distribution meter “UPA-150EX” manufactured by Nikkiso Co., Ltd.).

  The laminated surface of the first conductive layer of the base film may be subjected to a hydrophilic treatment. As described above, the surface tension of the conductive ink with respect to the base film is reduced by applying the hydrophilic treatment to the laminated surface of the first conductive layer of the base film, and the conductive ink is formed on the surface of the base film. Becomes easier to apply uniformly. Thereby, it becomes easy to form the first conductive layer with a uniform thickness on the surface of the base film.

  The metal may be copper. Thus, when the said metal is copper, the electroconductivity of a 1st conductive layer becomes high and the printed wiring board excellent in electroconductivity can be created.

  A printed wiring board according to another aspect of the present invention is a printed wiring board having a conductive pattern, wherein the conductive pattern is applied to the first conductive layer and the second conductive layer of the printed wiring board substrate. Or it is a printed wiring board formed by using a semi-additive method.

  Since the printed wiring board is manufactured using the printed wiring board substrate, the printed wiring board can be formed thin, and the adhesion between the base film and the conductive layer is large, and the conductive layer peels off from the base film. hard.

  According to still another aspect of the present invention, there is provided a method for manufacturing a printed wiring board substrate, wherein the first conductive layer is formed by applying and heating a conductive ink containing metal particles on at least one surface of an insulating base film. Forming a second conductive layer on the surface of the first conductive layer opposite to the base film by electroless plating using a plating solution containing nickel, and forming the first conductive layer, The substrate for printed wiring boards, wherein nickel is present in the two conductive layers and the base film, and the amount of nickel in the interface vicinity layer of 500 nm or less from the interface between the first conductive layer and the base film is 1% by mass or more as determined by EDX analysis It is a manufacturing method.

  In the printed wiring board substrate manufacturing method, a first conductive layer is formed by applying and heating a conductive ink containing metal particles on at least one surface of a base film, and the base of the first conductive layer is formed by electroless plating. Since the second conductive layer is formed on the surface opposite to the film, expensive vacuum equipment necessary for physical vapor deposition such as sputtering is not required. Therefore, the size of the printed wiring board substrate manufactured by the method for manufacturing a printed wiring board substrate is not limited by the vacuum equipment. In addition, since the method for manufacturing a printed wiring board substrate performs electroless plating using a plating solution containing nickel, there is a predetermined amount or more of nickel in the interface vicinity layer of the first conductive layer and the base film, As a result, the adhesion between the base film and the first conductive layer is improved. Note that the second conductive layer may be formed by electroplating after electroless plating.

[Details of the embodiment of the present invention]
Hereinafter, a printed wiring board substrate, a printed wiring board, and a method for manufacturing a printed wiring board substrate according to embodiments of the present invention will be described with reference to the drawings.

[PCB board]
The printed wiring board substrate shown in FIGS. 1 and 2 includes an insulating base film 1 and a first conductive layer 2 laminated on one surface of the base film 1 by application of conductive ink containing metal particles. The second conductive layer 3 is laminated on the surface of the first conductive layer 2 opposite to the base film 1 by electroless plating. Further, nickel is present in the first conductive layer 2, the second conductive layer 3 and the base film 1.

<Base film>
The base film 1 constituting the printed wiring board substrate has an insulating property. Examples of the material of the base film 1 include flexible resins such as polyimide, liquid crystal polymer, fluororesin, polyethylene terephthalate, and polyethylene naphthalate, paper phenol, paper epoxy, glass composite, glass epoxy, and Teflon (registered trademark). It is possible to use a rigid material such as a glass substrate, or a rigid flexible material in which a hard material and a soft material are combined. Among these, polyimide is particularly preferable because of its high bonding strength with metal oxides.

  Although the thickness of the said base film 1 is set by the printed wiring board using the said board | substrate for printed wiring boards, it is not specifically limited, For example, as a minimum of the average thickness of the said base film 1, 5 micrometers is preferable, 12 micrometers Is more preferable. On the other hand, the upper limit of the average thickness of the base film 1 is preferably 2 mm, more preferably 1.6 mm. When the average thickness of the base film 1 is less than the lower limit, the strength of the base film 1 may be insufficient. Conversely, when the average thickness of the base film 1 exceeds the above upper limit, it may be difficult to make the printed wiring board thinner.

  The base film 1 is preferably subjected to a hydrophilic treatment on the surface on which the conductive ink is applied. As the hydrophilic treatment, for example, plasma treatment for irradiating plasma to make the surface hydrophilic, alkali treatment for making the surface hydrophilic with an alkaline solution, or the like can be employed. By subjecting the base film 1 to the hydrophilic treatment, the surface tension of the conductive ink with respect to the base film 1 is reduced, so that it becomes easy to uniformly apply the conductive ink to the base film 1.

<First conductive layer>
The first conductive layer 2 is laminated on one surface of the base film 1 by applying a conductive ink containing metal particles. In the printed wiring board substrate, since the first conductive layer 2 is formed by application of conductive ink, one surface of the base film 1 can be easily covered with a conductive film. Note that the first conductive layer 2 is subjected to a heat treatment after the application of the conductive ink in order to remove unnecessary organic substances and the like in the conductive ink and securely fix the metal particles to one surface of the base film 1. Is preferred.

(Conductive ink)
The conductive ink for forming the first conductive layer 2 contains metal particles as a conductive substance that provides conductivity. In this embodiment, the conductive ink includes metal particles, a dispersant that disperses the metal particles, and a dispersion medium. By applying using such conductive ink, the first conductive layer 2 made of fine metal particles is laminated on one surface of the base film 1.

  Although the metal which comprises the metal particle contained in the said conductive ink is not specifically limited, From a viewpoint of the adhesive force improvement between the 1st conductive layer 2 and the base film 1, the metal oxidation based on the metal is carried out. Preferred is one in which a group derived from a product or a metal oxide thereof and a metal hydroxide based on the metal or a group derived from the metal hydroxide are generated, for example, copper, nickel, aluminum, gold or silver Can be used. Among these, copper is preferably used as a metal having good conductivity and excellent adhesion to the base film 1.

  1 nm is preferable and, as for the minimum of the average particle diameter of the metal particle contained in the said conductive ink, 30 nm is more preferable. Moreover, 500 nm is preferable and, as for the upper limit of the average particle diameter of the said metal particle, 100 nm is more preferable. When the average particle diameter of the metal particles is less than the lower limit, the dispersibility and stability of the metal particles in the conductive ink may be reduced. Moreover, when the average particle diameter of the metal particles exceeds the upper limit, the metal particles may be easily precipitated, and the density of the metal particles is difficult to be uniform when the conductive ink is applied.

  The lower limit of the average thickness of the first conductive layer 2 is preferably 0.05 μm, and more preferably 0.1 μm. On the other hand, the upper limit of the average thickness of the first conductive layer 2 is preferably 2 μm, and more preferably 1.5 μm. When the average thickness of the said 1st conductive layer 2 is less than the said minimum, there exists a possibility that the part in which a metal particle does not exist in the thickness direction may increase, and electroconductivity may fall. Conversely, if the average thickness of the first conductive layer 2 exceeds the upper limit, it may be difficult to reduce the thickness of the conductive layer.

<Second conductive layer>
The second conductive layer 3 is laminated on the surface of the first conductive layer 2 opposite to the base film 1 by electroless plating. As described above, since the second conductive layer 3 is formed by electroless plating, the space between the metal particles forming the first conductive layer 2 is filled with the metal of the second conductive layer 3. If voids remain in the first conductive layer 2, the void portion becomes a starting point of breakage, and the first conductive layer 2 is easily peeled off from the base film 1, but this void portion is filled with the second conductive layer 3. As a result, peeling of the first conductive layer 2 is prevented.

  As the metal used for the electroless plating, copper, nickel, silver or the like having good conductivity can be used. However, when copper is used for the metal particles forming the first conductive layer 2, the first conductive layer 2 is used. It is preferable to use copper or nickel in consideration of the adhesion to the substrate. In this embodiment, when a metal other than nickel is used for electroless plating, a plating solution containing nickel or a nickel compound in addition to the plating metal is used for the electroless plating.

  The lower limit of the average thickness of the second conductive layer 3 formed by electroless plating is preferably 0.2 μm, and more preferably 0.3 μm. On the other hand, the upper limit of the average thickness of the second conductive layer 3 formed by electroless plating is preferably 1 μm, and more preferably 0.5 μm. When the average thickness of the second conductive layer 3 formed by the electroless plating is less than the lower limit, the second conductive layer 3 may not be sufficiently filled in the gap portion of the first conductive layer 2 and the conductivity may be lowered. . On the other hand, when the average thickness of the second conductive layer 3 formed by the electroless plating exceeds the upper limit, the time required for the electroless plating becomes longer and the productivity may be lowered.

  It is also preferable to form the second conductive layer 3 thickly by performing electroplating after forming the thin layer by electroless plating. By performing electroplating after electroless plating, the thickness of the conductive layer can be adjusted easily and accurately, and a conductive layer having a thickness necessary for forming a printed wiring in a relatively short time can be formed. As the metal used for the electroplating, copper, nickel, silver or the like having good conductivity can be used.

  The thickness of the second conductive layer 3 after the electroplating is not particularly limited and is set depending on what kind of printed circuit is created. For example, the lower limit of the average thickness of the second conductive layer 3 after the electroplating Is preferably 1 μm, and more preferably 2 μm. On the other hand, the upper limit of the average thickness of the second conductive layer 3 after the electroplating is preferably 100 μm, and more preferably 50 μm. When the average thickness of the second conductive layer 3 after the electroplating is less than the lower limit, the conductive layer may be easily damaged. Conversely, if the average thickness of the second conductive layer 3 after the electroplating exceeds the upper limit, it may be difficult to make the printed wiring board thinner.

(Nickel content)
In the vicinity of the interface 4 (first interface) between the base film 1 and the first conductive layer 2, nickel is aggregated. This nickel is nickel derived from nickel or a nickel compound contained in the plating solution used in the electroless plating, and is deposited in the vicinity of the first interface 4 during the electroless plating.

  When the area within the first conductive layer 2 and the base film 1 that is 500 nm or less from the first interface 4 is the interface vicinity layer 6, the lower limit of the nickel amount in the interface vicinity layer 6 is 1% by mass as determined by EDX analysis. And 3% by mass is more preferred. On the other hand, the upper limit of the amount of nickel in the interface vicinity layer 6 is preferably 10% by mass and more preferably 8% by mass as determined by EDX analysis. When the amount of nickel in the interface vicinity layer 6 is less than the lower limit, the effect of reducing the residual stress due to the presence of nickel is lowered, so that the adhesion between the base film 1 and the first conductive layer 2 may not be sufficiently improved. There is. On the contrary, when the nickel amount in the interface vicinity layer 6 exceeds the upper limit, the production cost of the printed wiring board substrate may increase due to an increase in the nickel amount contained in the plating solution or an increase in the plating amount.

  As described above, in the printed wiring board substrate, since nickel is aggregated in the vicinity of the first interface 4, more nickel is present in the vicinity of the first interface 4 than in the second conductive layer 3. Specifically, as shown in FIG. 2, when the A layer 7 is 500 nm or less from the second interface 5 of the second conductive layer 3, the nickel mass ratio of the interface vicinity layer 6 is the nickel of the A layer 7. It is larger than the mass ratio. Thus, the presence of a large amount of nickel in the vicinity of the first interface 4 provides an excellent adhesion between the base film 1 and the first conductive layer 2.

  In addition, nickel derived from nickel or a nickel compound contained in the plating solution used in the electroless plating is also deposited on the second conductive layer 3, the first conductive layer 2 and the base film 1 during the electroless plating, and the second conductive Also present in layer 3, first conductive layer 2 and base film 1.

  In the printed wiring board substrate, more nickel is present in the base film 1 than in the second conductive layer 3 due to the aggregation of nickel in the vicinity of the first interface 4. Specifically, as shown in FIG. 2, when the B layer 8 is 1 μm or less from the first interface 4 of the base film 1, the nickel mass ratio of the B layer 8 is the mass ratio of nickel of the A layer 7. Bigger than. Thus, the presence of a large amount of nickel in the base film 1 can effectively reduce the residual stress of the base film 1 that greatly affects the peeling between the first conductive layer and the base film. The adhesion between the conductive layer 2 is improved.

  The lower limit of the amount of nickel in the B layer 8 is preferably 1% by mass and more preferably 2% by mass as determined by EDX analysis. On the other hand, the upper limit of the amount of nickel in the B layer 8 is preferably 5% by mass as determined by EDX analysis, and more preferably 4% by mass. When the amount of nickel in the B layer 8 is less than the lower limit, the residual stress of the base film 1 is not sufficiently reduced, and the adhesion between the base film 1 and the first conductive layer 2 may not be sufficiently improved. . On the contrary, when the amount of nickel in the B layer 8 exceeds the upper limit, the amount of nickel in the near-interface layer 6 is relatively reduced, so that the residual stress in the near-interface layer 6 is not sufficiently reduced. There is a possibility that the adhesion between the conductive layer 2 and the conductive layer 2 is not sufficiently improved.

  The lower limit of the amount of nickel in the A layer 7 is preferably 0.5% by mass as determined by EDX analysis, and more preferably 1% by mass. On the other hand, the upper limit of the amount of nickel in the A layer 7 is preferably 3% by mass and more preferably 2% by mass as determined by EDX analysis. When the amount of nickel in the A layer 7 is less than the lower limit, the residual stress of the second conductive layer 3 is not reduced, and the adhesion between the first conductive layer 2 and the second conductive layer 3 may be reduced. . Conversely, when the amount of nickel in the A layer 7 exceeds the upper limit, the production cost of the printed wiring board substrate may increase due to an increase in the amount of nickel contained in the plating solution or an increase in the amount of plating.

  When the region other than the interface vicinity layer 6 of the first conductive layer 2 is the C layer 9 as shown in FIG. 2, the lower limit of the nickel amount in the C layer 9 is 1% by mass as determined by EDX analysis. Preferably, 2 mass% is more preferable. On the other hand, the upper limit of the amount of nickel in the C layer 9 is preferably 6% by mass and more preferably 5% by mass as determined by EDX analysis. When the amount of nickel in the C layer 9 is less than the lower limit, the residual stress of the first conductive layer 2 is not reduced, and the adhesion between the base film 1 and the first conductive layer 2 may not be sufficiently improved. . On the other hand, when the amount of nickel in the C layer 9 exceeds the upper limit, the production cost of the printed wiring board substrate may increase due to an increase in the amount of nickel contained in the plating solution or an increase in the amount of plating.

  When palladium is used as the electroless plating catalyst, palladium is also included in the first conductive layer 2, the second conductive layer 3, and the base film 1 in the same manner as nickel. Thus, when palladium is contained, it is preferable that the mass ratio of palladium of the B layer 8 is larger than the mass ratio of palladium of the A layer 7 and larger than the mass ratio of palladium of the C layer 9. Thus, by distributing palladium so that the mass ratio in the base film 1 is larger than the mass ratio of the first conductive layer 2 and the second conductive layer 3, plating at the interface between the base film 1 and the first conductive layer 2 is performed. Precipitation becomes denser and adhesion between the base film 1 and the first conductive layer 2 is improved. In addition, it is not always necessary to use palladium as a catalyst for the electroless plating. When palladium is not used as the catalyst, the first conductive layer 2, the second conductive layer 3 and the base film of the printed wiring board substrate are used. 1 does not contain palladium.

[Method of manufacturing printed circuit board]
The method for manufacturing a printed wiring board substrate includes a step of forming a first conductive layer by applying and heating conductive ink containing metal particles on one surface of an insulating base film (first conductive layer forming step). And a step of forming a second conductive layer on the surface of the first conductive layer opposite to the base film by electroless plating using a plating solution containing nickel (second conductive layer forming step). The printed wiring board substrate manufactured by the method for manufacturing a printed wiring board substrate includes nickel in the first conductive layer, the second conductive layer, and the base film, and is 500 nm from the interface between the first conductive layer and the base film. The amount of nickel in the interface near layer below is 1% by mass or more as determined by EDX analysis.

<First conductive layer forming step>
In the first conductive layer forming step, as shown in FIG. 3A, a conductive ink containing metal particles is applied to the surface of the base film 1, dried, and then subjected to heat treatment.

(Method for producing metal particles)
Here, a method for producing metal particles dispersed in the conductive ink will be described. The metal particles can be produced by a high temperature treatment method, a liquid phase reduction method, a gas phase method, or the like.

In order to produce the above metal particles by the liquid phase reduction method, for example, a water-soluble metal compound that is a source of metal ions that form metal particles in water and a dispersant are dissolved, and a reducing agent is added. What is necessary is just to make a metal ion reduce-react for a fixed time. In the case of the liquid phase reduction method, the metal particles to be produced have a spherical or granular shape and can be made into fine particles. For example, in the case of copper, copper (II) nitrate (Cu (NO ₃ ) ₂ ), copper (II) sulfate pentahydrate (CuSO ₄ .5H ₂ ) as the water-soluble metal compound that is the basis of the metal ions. O) and the like. In the case of silver, silver nitrate (I) (AgNO ₃ ), silver methanesulfonate (CH ₃ SO ₃ Ag), etc. In the case of gold, tetrachloroauric (III) acid tetrahydrate (HAuCl ₄ .4H ₂ O) In the case of nickel, nickel chloride (II) hexahydrate (NiCl ₂ · 6H ₂ O), nickel nitrate (II) hexahydrate (Ni (NO ₃ ) ₂ · 6H ₂ O) and the like can be mentioned. . For other metal particles, water-soluble compounds such as chlorides, nitric acid compounds and sulfuric acid compounds can be used.

  As a reducing agent when producing metal particles by a liquid phase reduction method, various reducing agents capable of reducing and precipitating metal ions in a liquid phase (aqueous solution) reaction system can be used. Examples of the reducing agent include sodium borohydride, sodium hypophosphite, hydrazine, transition metal ions such as trivalent titanium ions and divalent cobalt ions, reducing sugars such as ascorbic acid, glucose and fructose, ethylene Examples thereof include polyhydric alcohols such as glycol and glycerin. Among these, the titanium redox method is a method in which metal ions are reduced by a redox action when trivalent titanium ions are oxidized to tetravalent and metal particles are precipitated. The metal particles obtained by the titanium redox method have small and uniform particle diameters, and the titanium redox method can make the shape of the metal particles spherical or granular. Therefore, by using the titanium redox method, the metal particles are filled with higher density, and the first conductive layer 2 can be formed in a denser layer.

  To adjust the particle size of the metal particles, adjust the type and blending ratio of the metal compound, dispersant, and reducing agent, and adjust the stirring speed, temperature, time, pH, etc. when reducing the metal compound. That's fine. For example, the pH of the reaction system is preferably 7 or more and 13 or less in order to obtain metal particles having a minute particle size as in this embodiment. At this time, the pH of the reaction system can be adjusted to the above range by using a pH adjuster. As this pH adjuster, a general acid or alkali such as hydrochloric acid, sulfuric acid, sodium hydroxide, sodium carbonate or the like is used. In particular, in order to prevent deterioration of peripheral members, alkali metal or alkaline earth metal, Nitric acid and ammonia which do not contain halogen elements such as chlorine and impurity elements such as sulfur, phosphorus and boron are preferable.

(Adjustment of conductive ink)
Next, a method for adjusting the conductive ink will be described. As the dispersant contained in the conductive ink, various dispersants having a molecular weight of 2,000 to 300,000 and capable of favorably dispersing metal particles precipitated in the dispersion medium can be used. By using a dispersant having a molecular weight in the above range, the metal particles can be favorably dispersed in the dispersion medium, and the film quality of the obtained first conductive layer 2 can be made dense and defect-free. When the molecular weight of the dispersant is less than the lower limit, the effect of preventing the aggregation of the metal particles and maintaining the dispersion may not be sufficiently obtained. As a result, the first conductive layer 2 laminated on the base film 1 may be obtained. May not be able to be made dense with few defects. On the other hand, when the molecular weight of the dispersant exceeds the above upper limit, the bulk of the dispersant is too large, and in the heat treatment performed after the application of the conductive ink, there is a risk of inhibiting the sintering of the metal particles and generating voids. Moreover, when the volume of a dispersing agent is too large, there exists a possibility that the denseness of the film quality of the 1st conductive layer 2 may fall, or the decomposition residue of a dispersing agent may reduce electroconductivity.

  The dispersant preferably does not contain sulfur, phosphorus, boron, halogen, and alkali from the viewpoint of preventing deterioration of parts. Preferred dispersants are those having a molecular weight in the above range, amine-based polymer dispersants such as polyethyleneimine and polyvinylpyrrolidone, and hydrocarbon-based hydrocarbons having a carboxylic acid group in the molecule such as polyacrylic acid and carboxymethylcellulose. Polar groups such as polymer dispersants, poval (polyvinyl alcohol), styrene-maleic acid copolymers, olefin-maleic acid copolymers, or copolymers having a polyethyleneimine moiety and a polyethylene oxide moiety in one molecule The polymer dispersing agent which has can be mentioned.

  The dispersant can also be added to the reaction system in the form of a solution dissolved in water or a water-soluble organic solvent. As a content rate of a dispersing agent, 1 to 60 mass parts is preferable per 100 mass parts of metal particles. The dispersing agent surrounds the metal particles to prevent aggregation and disperse the metal particles satisfactorily. However, when the content of the dispersing agent is less than the lower limit, this aggregation preventing effect may be insufficient. On the other hand, when the content ratio of the dispersant exceeds the upper limit, during the heat treatment after the coating of the conductive ink, there is a risk that an excessive dispersant inhibits firing including sintering of the metal particles, and voids are generated. In addition, the decomposition residue of the polymer dispersant may remain as an impurity in the first conductive layer 2 to reduce the conductivity.

  The content ratio of water serving as a dispersion medium in the conductive ink is preferably 20 parts by mass or more and 1900 parts by mass or less per 100 parts by mass of the metal particles. The water of the dispersion medium sufficiently swells the dispersing agent to favorably disperse the metal particles surrounded by the dispersing agent. However, when the content ratio of the water is less than the lower limit, the swelling effect of the dispersing agent by water can be reduced. May be insufficient. On the other hand, when the content ratio of the water exceeds the upper limit, the ratio of the metal particles in the conductive ink is reduced, and the favorable first conductive layer 2 having the necessary thickness and density cannot be formed on the surface of the base film 1. There is a fear.

  Various organic solvents that are water-soluble can be used as the organic solvent blended into the conductive ink as necessary. Specific examples thereof include alcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, sec-butyl alcohol and tert-butyl alcohol, ketones such as acetone and methyl ethyl ketone, Examples thereof include polyhydric alcohols such as ethylene glycol and glycerin and other esters, and glycol ethers such as ethylene glycol monoethyl ether and diethylene glycol monobutyl ether.

  The content ratio of the water-soluble organic solvent is preferably 30 parts by mass or more and 900 parts by mass or less per 100 parts by mass of the metal particles. When the content rate of the said water-soluble organic solvent is less than the said minimum, there exists a possibility that the effect of the viscosity adjustment and vapor pressure adjustment of the dispersion liquid by the said organic solvent may not fully be acquired. On the other hand, when the content ratio of the water-soluble organic solvent exceeds the above upper limit, the swelling effect of the dispersant due to water becomes insufficient, and the metal particles may aggregate in the conductive ink.

  In addition, when producing metal particles by the liquid phase reduction method, the metal particles deposited in the liquid phase (aqueous solution) reaction system are once powdered through steps such as filtration, washing, drying, and crushing. The conductive ink can be adjusted by using one. In this case, a powdered metal particle, water as a dispersion medium, a dispersant, and, if necessary, a water-soluble organic solvent are blended in a predetermined ratio to obtain a conductive ink containing metal particles. Can do. At this time, it is preferable to adjust the conductive ink using a liquid phase (aqueous solution) in which metal particles are deposited as a starting material. Specifically, the liquid phase (aqueous solution) containing the precipitated metal particles is subjected to treatment such as ultrafiltration, centrifugation, washing with water, and electrodialysis to remove impurities, and if necessary, concentrated to remove water. . Or conversely, after adding water and adjusting the density | concentration of a metal particle, the electroconductive ink containing a metal particle is adjusted by mix | blending a water-soluble organic solvent in a predetermined | prescribed ratio further as needed. In this method, generation of coarse and irregular particles due to agglomeration of metal particles during drying can be prevented, and the dense and uniform first conductive layer 2 can be easily formed.

(Applying conductive ink)
As a method of applying the conductive ink in which metal particles are dispersed on one surface of the base film 1, a spin coating method, a spray coating method, a bar coating method, a die coating method, a slit coating method, a roll coating method, a dip coating method. A conventionally known coating method such as the above can be used. Alternatively, the conductive ink may be applied to only a part of one surface of the base film 1 by screen printing, a dispenser, or the like.

(Heat treatment)
A conductive ink is applied to one surface of the base film 1 and dried, followed by heat treatment. The first conductive layer 2 fixed to one surface of the base film 1 is obtained as a baked coating layer by applying heat treatment after applying conductive ink to one surface of the base film 1. By heat treatment, the dispersing agent and other organic substances contained in the applied conductive ink are volatilized and decomposed and removed from the coating layer, so that the remaining metal particles are in the sintered state or in the previous stage before sintering. It will be in the state which closely_contact | adhered to and solid-bonded.

  Further, in the vicinity of the interface 4 between the first conductive layer 2 and the base film 1, the metal particles are oxidized by the heat treatment, and a metal hydroxide based on the metal of the metal particles or a group derived from the metal hydroxide is generated. In this way, a metal oxide based on the above metal or a group derived from the metal oxide is generated. Specifically, for example, when copper is used as the metal particles, copper oxide and copper hydroxide are generated in the vicinity of the interface between the first conductive layer 2 and the base film 1, but more copper oxide is generated. Since the copper oxide produced in the vicinity of the first interface 4 is strongly bonded to the polyimide constituting the base film 1, the adhesion between the first conductive layer 2 and the base film 1 is increased.

  The heat treatment is performed in an atmosphere containing a certain amount of oxygen. The lower limit of the oxygen concentration in the atmosphere during the heat treatment is 1 ppm, and 10 ppm is more preferable. Moreover, as an upper limit of the said oxygen concentration, it is 10,000 ppm and 1,000 ppm is more preferable. When the oxygen concentration is less than the lower limit, the amount of copper oxide generated in the vicinity of the interface of the first conductive layer 2 is reduced, and the effect of improving the adhesion between the first conductive layer 2 and the base film 1 due to the copper oxide is sufficient. May not be obtained. On the other hand, when the oxygen concentration exceeds the upper limit, the metal particles are excessively oxidized and the conductivity of the first conductive layer 2 may be lowered.

  As a minimum of the temperature of the above-mentioned heat treatment, 150 ° C is preferred and 200 ° C is more preferred. Moreover, as an upper limit of the temperature of the said heat processing, 500 degreeC is preferable and 400 degreeC is more preferable. When the temperature of the heat treatment is lower than the lower limit, the amount of metal oxide generated in the vicinity of the interface 4 of the first conductive layer 2 is reduced, and the adhesion between the first conductive layer 2 and the base film 1 is improved by the metal oxide. The effect may not be obtained sufficiently. On the other hand, when the temperature of the heat treatment exceeds the upper limit, the base film 1 may be deformed when the base film 1 is an organic resin such as polyimide.

<Second conductive layer forming step>
In the second conductive layer forming step, as shown in FIG. 3B, the surface of the first conductive layer 2 laminated on the base film 1 in the first conductive layer forming step is electrolessly plated on the surface opposite to the base film 1. The second conductive layer 3 is formed.

  In addition, the electroless plating is, for example, a cleaner process, a water washing process, an acid treatment process, a water washing process, a pre-dip process, an activator process, a water washing process, a reduction process, a water washing process, a metal layer forming process (chemical copper process, chemical nickel process). Etc.), electroless plating is performed together with the water washing process, the drying process and the like. Of these processes, the activator process is not an essential process and may not be performed during electroless plating.

  As described above, copper, nickel, silver, or the like can be used as a metal used for electroless plating. For example, when copper plating is performed, a copper plating solution containing a small amount of nickel is used as a copper plating solution used in electroless plating. By using a copper plating solution containing nickel or a nickel compound, the low-stress second conductive layer 3 can be formed. As said copper plating liquid, what contains 0.1 mol or more and 60 mol or less nickel with respect to 100 mol copper, for example is used. Moreover, you may mix | blend other components, such as a complexing agent, a reducing agent, and a pH adjuster, with the said copper plating solution suitably.

  In the method for manufacturing a substrate for a printed wiring board, by performing electroless plating using a plating solution containing nickel or a nickel compound, nickel derived from the nickel or nickel compound contained in the plating solution is not electrolyzed. It is deposited on the first conductive layer 2, the second conductive layer 3 and the base film 1. Since this nickel is distributed so as to aggregate in the interface vicinity layer 6, the residual stress of the base film 1 and the first conductive layer 2 is reduced in the printed wiring board substrate. In particular, since the residual stress in the interface vicinity layer 6 is greatly reduced, the adhesion between the first conductive layer 2 and the base film 1 is significantly improved.

  In the electroless plating, palladium may be used as a plating metal deposition catalyst. When palladium is used as the deposition catalyst, for example, in the activator step, palladium ion is adsorbed on the surface of the first conductive layer 2 by bringing the surface of the first conductive layer 2 into contact with the palladium chloride solution, and the first step in the reduction step. The palladium ions adsorbed on the conductive layer 2 are reduced to metallic palladium. For example, in the case of performing electroless copper plating, in the chemical copper process, a copper film is formed on the surface of the first conductive layer 2 using palladium as a catalyst, for example, by dipping in an aqueous solution containing copper sulfate and formalin. It is formed. Further, for example, when performing electroless nickel plating, in the chemical nickel step, nickel is applied to the surface of the first conductive layer 2 using palladium as a catalyst by immersing in an aqueous solution containing, for example, nickel sulfate and sodium hypophosphite. A film is formed.

  In the method for manufacturing a printed wiring board substrate, by performing electroless plating using palladium as a deposition catalyst, the reduced palladium of palladium ions adsorbed on the first conductive layer 2 becomes the first conductive during electroless plating. It moves from the surface of the layer 2 toward the base film 1. The palladium thus moved is distributed such that the mass ratio of the base film 1 is larger than that of the first conductive layer 2 and the second conductive layer 3. Since a large amount of palladium is contained in the base film 1 and plating deposition at the interface between the base film 1 and the first conductive layer 2 becomes denser, the adhesion between the base film 1 and the first conductive layer 2 is increased. Power improves more.

  When an average thickness of 1 μm or more is required as the conductive layer, for example, after electroless plating, electroplating is further performed until the required thickness of the conductive layer is reached. In this electroplating, for example, a known electroplating bath according to a metal to be plated such as copper, nickel, silver, etc. is used, and an appropriate condition is selected, so that a conductive layer having a predetermined thickness is quickly formed without defects. Can be done as follows.

[Printed wiring board]
The printed wiring board is manufactured by forming a conductive pattern on the printed wiring board substrate shown in FIG. The conductive pattern is formed on the first conductive layer 2 and the second conductive layer 3 of the printed wiring board substrate using a subtractive method or a semi-additive method.

[Method of manufacturing printed wiring board]
Next, an embodiment of a method for manufacturing the printed wiring board using the printed wiring board substrate will be described. Here, a case where a conductive pattern is formed by a subtractive method will be described.

  First, as shown in FIG. 4A, a photosensitive resist 10 is formed on one surface of the printed wiring board substrate adjusted to a predetermined size. Next, as shown in FIG. 4B, patterning corresponding to the conductive pattern is performed on the resist 10 by exposure, development, or the like. Next, as shown in FIG. 4C, the second conductive layer 3 and the first conductive layer 2 other than the conductive pattern are removed by etching using the resist 10 as a mask. Finally, as shown in FIG. 4D, the remaining resist 10 is removed to obtain a printed wiring board in which the conductive pattern 11 is formed on the base film 1.

  Although the printed wiring board manufacturing method for forming a circuit by the subtractive method has been described here, the printed wiring board can be manufactured even if the circuit is formed by using another known manufacturing method such as a semi-additive method. Since the printed wiring board is manufactured using the printed wiring board substrate, the printed wiring board is sufficiently thin to meet the demand for high-density printed wiring, and the base film 1 and the first conductive layer 2 are in close contact with each other. The force is large and the conductive layer is difficult to peel from the base film 1.

〔advantage〕
In the printed wiring board substrate, a predetermined amount of nickel is present in the vicinity of the interface between the base film and the first conductive layer, the adhesion between the first conductive layer and the base film is large, and the conductive layer is difficult to peel off from the base film.

  In addition, since the printed wiring board substrate can obtain a large adhesion force between the first conductive layer and the base film without using an adhesive, the adhesion force between the conductive layer and the base film is large and high density. Can be manufactured at low cost.

[Other Embodiments]
The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is not limited to the configuration of the embodiment described above, but is defined by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims. The

  In the said embodiment, although it was set as the structure which laminates | stacks the 1st conductive layer 2 and the 2nd conductive layer 3 on the one surface of the base film 1, a 1st conductive layer and a 2nd conductive on both surfaces of a base film with the same formation method. It is good also as a board | substrate for double-sided printed wiring boards of the structure which laminates | stacks a layer. Moreover, you may form a conductive layer with another method in the other surface of the board | substrate for printed wiring boards obtained by the said embodiment. For example, a conductive layer may be formed on the other surface of the printed wiring board substrate by electroplating.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example]
By changing the condition of the amount of nickel included in the electroless plating solution for forming the second conductive layer, the test No. in Table 1 was used as an example. 1-No. 6 types of printed wiring board substrates were manufactured.

  Test No. in Table 1 The printed wiring board substrate shown in FIG. 1 was produced as follows. First, copper particles having an average particle diameter of 60 nm were dispersed in solvent water to prepare a conductive ink having a copper concentration of 26% by mass. Next, a polyimide film having an average thickness of 25 μm (“Kapton EN-S” manufactured by Toray DuPont Co., Ltd.) was used as an insulating base film, and this conductive ink was applied to one surface of the polyimide film, and in the atmosphere. Was dried to form a first conductive layer having an average thickness of 0.15 μm. Then, heat treatment was performed at 350 ° C. for 30 minutes in a nitrogen atmosphere having an oxygen concentration of 100 ppm. Next, copper electroless plating was performed on one surface of the first conductive layer to form a second conductive layer having an average thickness of 0.4 μm by electroless plating. Here, as an electroless copper plating solution used for electroless plating, a solution containing 0.1 mol of nickel with respect to 100 mol of copper was used. Further, electroplating of copper was performed to obtain a printed wiring board substrate having a total average thickness of conductive layers made of copper of 18 μm.

  Further, as the electroless copper plating solution used for electroless plating, the above test No. 1 was used except that one containing 1 mol of nickel per 100 mol of copper was used. In the same manner as the printed wiring board substrate shown in FIG. 2 printed wiring board substrates were obtained. Further, as the electroless copper plating solution used for electroless plating, the above test No. 1 was used except that one containing 20 mol of nickel with respect to 100 mol of copper was used. In the same manner as the printed wiring board substrate shown in FIG. 3 printed wiring board substrates were obtained. Further, as the electroless copper plating solution used for electroless plating, the above test No. 1 was used except that one containing 60 mol of nickel with respect to 100 mol of copper was used. In the same manner as the printed wiring board substrate shown in FIG. 4 printed wiring board substrates were obtained.

  In addition, an activator step is carried out before electroless plating, and the polyimide film on which the first conductive layer is formed is immersed in 0.3 g / L of palladium chloride at 45 ° C. for 30 seconds on the surface of the first conductive layer. Except that metal palladium was deposited and then electroless plating was performed, the above test Nos. In the same manner as the printed wiring board substrate shown in FIG. 5 printed wiring board substrates were obtained. In addition, Test No. When the printed wiring board substrate other than 5 is prepared, the activator process is not performed.

[Comparative example]
Except that nickel was not included in the electroless copper plating solution used for electroless plating, the above test Nos. In the same manner as the printed wiring board substrate shown in FIG. A printed wiring board substrate No. 6 was obtained.

<Adhesion evaluation>
Test No. 1-No. For the printed wiring board substrate of 6, the peel strength (g / cm) between the polyimide film and the conductive layer was measured, and the adhesion between the polyimide film and the conductive layer was evaluated. The peel strength was measured according to JIS-C6471 (1995), and was measured by a method in which the conductor layer was peeled away from the polyimide film in the 180 ° direction. Table 1 shows the measurement results of peel strength.

<Measurement of nickel content and palladium content>
Test No. 1-No. For the cross section of the printed wiring board substrate of No. 6, using an energy dispersive X-ray analyzer (Hitachi High-Technologies Corporation scanning electron microscope “SU8020”), the EDX mapping at an acceleration voltage of 3 kV was observed, The amount of nickel and the amount of palladium in the A layer and the B layer were measured. Table 1 shows the measurement results of the nickel amount and the palladium amount of each printed wiring board substrate.

[Evaluation results]
From the results in Table 1, the test No. 1-No. The peel strength of the printed wiring board substrate No. 5 is as large as 700 g / cm or more, and it can be seen that the adhesion between the polyimide film and the conductive layer is large. In contrast, test no. The peel strength of the printed wiring board substrate No. 6 is small, and it can be said that the conductive layer is easily peeled off from the polyimide film.

  Test No. 1-No. In the printed wiring board substrate of No. 5, since a large amount of nickel is present in the vicinity of the interface between the polyimide film and the conductive layer, no. It can be considered that the adhesion between the polyimide film and the conductive layer was significantly increased as compared with the printed wiring board substrate of No. 6. In addition, Test No. 1-No. From the peel strength of the printed wiring board substrate of No. 4, it can be said that as the amount of nickel in the vicinity of the interface between the polyimide film and the conductive layer increases, the adhesion between the polyimide film and the conductive layer improves.

  By performing the activator process, the test No. In the printed wiring board substrate of No. 5, palladium exists in the A layer and the B layer. Test No. 3 and test no. From the result of 5, it can be seen that even if palladium is present in the polyimide film, the effect of improving the adhesion between the polyimide film and the conductive layer due to the presence of nickel can be obtained.

  The printed wiring board substrate, the printed wiring board and the printed wiring board substrate manufacturing method of the present invention are suitable for printed wiring boards and the like that require high-density printed wiring because the conductive layer can be sufficiently thin at low cost. Used for.

DESCRIPTION OF SYMBOLS 1 Base film 2 1st conductive layer 3 2nd conductive layer 4 1st interface (interface of a base film and a 1st conductive layer)
5 Second interface (interface between the first conductive layer and the second conductive layer)
6 layer near interface 7 A layer 8 B layer 9 C layer 10 resist 11 conductive pattern

Claims (6)

An insulating base film;
A first conductive layer laminated on at least one surface of the base film by applying a conductive ink containing copper particles;
A second conductive layer laminated on the surface opposite to the base film of the first conductive layer by electroless plating,
There is nickel derived from the electroless plating on the first conductive layer, the second conductive layer and the base film,
The amount of nickel in the interface vicinity layer of 500 nm or less from the interface between the first conductive layer and the base film is 1% by mass or more and 10% by mass or less as determined by EDX analysis,
The mass ratio of nickel in the interface vicinity layer is larger than the mass ratio of nickel in the A layer of 500 nm or less from the interface between the second conductive layer and the first conductive layer,
A printed wiring board substrate, wherein the electroless plating is copper plating containing nickel. Palladium is present in the first conductive layer, the second conductive layer and the base film,
The mass proportion of palladium in the B layer of 1 μm or less from the interface with the first conductive layer of the base film is more than the mass proportion of palladium in the A layer of 500 nm or less from the interface with the first conductive layer of the second conductive layer. The printed wiring board substrate according to claim 1, which is large. The printed wiring board substrate according to claim 1 or 2, wherein an average particle diameter of the metal particles is 1 nm or more and 500 nm or less. The printed wiring board substrate according to claim 1 , wherein the laminated surface of the first conductive layer of the base film is subjected to a hydrophilic treatment. A printed wiring board having a conductive pattern,
The conductive pattern is formed by using a subtractive method or a semi-additive method on the first conductive layer and the second conductive layer of the printed wiring board substrate according to any one of claims 1 to 4. Printed wiring board. Forming a first conductive layer by applying and heating conductive ink containing copper particles on at least one surface of an insulating base film; and
Forming a second conductive layer on the surface of the first conductive layer opposite to the base film by electroless plating using a copper plating solution containing nickel,
There is nickel derived from the electroless plating on the first conductive layer, the second conductive layer and the base film,
Weight nickel near the interface layer from the interface following 500nm of the first conductive layer and the base film state, and are less than 10 mass% to 1 mass% in the quantification by EDX analysis,
A method for producing a printed wiring board substrate, wherein a mass ratio of nickel in the interface vicinity layer is larger than a mass ratio of nickel in the A layer of 500 nm or less from the interface between the second conductive layer and the first conductive layer .

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