JP2015041692A - Wiring board and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which can be thinned and has good flexibility, and a method for manufacturing the same.SOLUTION: The wiring board (1) contains a base material part (10) consisting of a metal layer (20) having a first main surface (22), a second main surface (24) and a side surface (24) and formed into the pattern shape, and a first insulation layer (30) arranged around the metal layer (20); a second insulation layer (30) covering the first main surface (22) of the metal layer (20); and a third insulation layer (50) covering the metal layer (20) and the second main surface (24).

Description

  The present invention relates to a wiring board and a manufacturing method thereof.

  In recent years, in order to reduce the thickness and flexibility of a wiring board, a thin base material having copper foil on both front and back surfaces has been used as the base material of the wiring board. However, in such a flexible wiring board, in order to electrically connect the wiring circuit on the front surface to the wiring circuit on the back surface, it is necessary to make a hole in the base material and form a metal layer in the opened hole by a plating method. For this reason, it is complicated to electrically connect the wiring circuit on the front surface to the wiring circuit on the back surface. Further, since a base material exists between the front surface wiring circuit and the rear surface wiring circuit, it is difficult to further reduce the thickness of the wiring substrate, and the heat conductivity from the front surface to the rear surface is not good.

  By the way, although it is not a wiring board, the semiconductor device and the base material for semiconductor element mounting which are excellent in heat conductivity and connection reliability, and can be reduced in thickness are known as a prior art (for example, refer patent document 1 and 2). ). Patent Document 1 includes a conductive metal pattern on which a semiconductor element is mounted. In a semiconductor device in which these are sealed with a sealing material, the conductive metal pattern is partially exposed on the side opposite to the semiconductor mounting surface. A semiconductor device is described. Patent Document 2 describes a semiconductor element mounting base material in which a semiconductor element mounting conductive metal pattern is formed on a peelable base material.

JP 2010-10275 A JP 2010-10276 A

  As a result of intensive studies, the inventors have applied the semiconductor device and the semiconductor element mounting substrate described in Patent Documents 1 and 2 to a wiring board, and can be thinned and have excellent flexibility. It has been found that a wiring board having a property can be obtained.

  An object of this invention is to provide the wiring board which can be reduced in thickness, and has the outstanding flexibility, and its manufacturing method.

As a result of intensive studies, the present inventors have found that the above-described problems can be solved by adopting the configuration shown below, and have completed the present invention.
That is, the present invention
[1] A base material portion including a metal layer having a first main surface, a second main surface, and side surfaces formed in a pattern and a first insulating layer disposed around the metal layer, a metal layer A wiring board including a second insulating layer covering the first main surface of the metal layer and a third insulating layer covering the second main surface of the metal layer.
[2] The wiring board according to [1], wherein the side surface of the metal layer has a tapered shape from the first main surface toward the second main surface.
[3] At least one of a part of the first main surface of the metal layer and a part of the second main surface of the metal layer is exposed from the second insulating layer or the third insulating layer. The wiring board according to the above [1] or [2].
[4] At least one of the second insulating layer and the third insulating layer is made of a cured product of a thermosetting and / or active energy ray-curable solder resist, according to the above [1] to [3]. The wiring board in any one.
[5] Step (A) of preparing a conductive substrate whose surface is covered with an insulating layer having an opening, Step (B) of forming a metal layer on the opening by plating, and pressure-sensitive adhesive on one surface A step (C) of preparing a release substrate having a layer and having flexibility, a step of causing the pressure-sensitive adhesive layer of the release substrate to adhere to the metal layer, and peeling the conductive substrate from the metal layer (D ), The step (E) of forming the first uncured insulating layer on the peeling substrate so that the genus layer is embedded, the first uncured insulating layer is cured, and the first cured insulating layer is Step (F) of forming, Step (G) of peeling the substrate for peeling from the metal layer and the first cured insulating layer, Second uncured insulation on the peeling surface of the metal layer and the first cured insulating layer A wiring substrate including a step (H) of forming a layer and a step (I) of curing the second uncured insulating layer to form a second cured insulating layer The method of production.
[6] In the step (B), the metal layer is formed in the opening so that the cross-sectional area in the planar direction of the conductive base material decreases as the distance from the insulating layer increases. Production method.
[7] In the step (E) and the step (H), at least one of the first uncured insulating layer and the second uncured insulating layer is formed such that a part of the metal layer is exposed. [5] or [6].
[8] In step (F) and step (I), the cured insulating layer is formed by photolithography so that a part of the metal layer is exposed from at least one of the first cured insulating layer and the second cured insulating layer. The method for manufacturing a wiring board according to [5] or [6], which is formed.
[9] The above [5] to [8], wherein at least one of the first uncured insulating layer and the second uncured insulating layer is made of a thermosetting and / or active energy ray curable solder resist. The manufacturing method of the wiring board in any one of.

  ADVANTAGE OF THE INVENTION According to this invention, the wiring board which can be reduced in thickness and has the outstanding flexibility, and its manufacturing method can be provided.

FIG. 1 is a plan view of a wiring board according to an embodiment of the present invention. FIG. 2 is a view showing a cross section taken along line A-A ′ of the wiring board shown in FIG. 1. FIG. 3 is a diagram for explaining a method of manufacturing a wiring board in one embodiment of the present invention. FIG. 4 is a diagram for explaining a method of manufacturing a wiring board in one embodiment of the present invention. Drawing 5 is a figure for explaining the process of carrying out process (A)-(D) by roll to roll method.

  Hereinafter, a wiring board according to an embodiment of the present invention will be described with reference to the drawings, but the present invention is not limited to those described in the drawings. FIG. 1 is a plan view of a wiring board 1 according to an embodiment of the present invention. FIG. 2 is a view showing a cross section taken along the line A-A ′ of the wiring board 1 shown in FIG. 1.

  As shown in FIGS. 1 and 2, the wiring board 1 according to an embodiment of the present invention has a first main surface 22, a second main surface 24, and a side surface 26, and a metal layer 20 formed in a pattern. And the first insulating layer 30 disposed around the metal layer 20, the second insulating layer 40 covering the first main surface 22 of the metal layer 20, and the second of the metal layer 20. A third insulating layer 50 covering the main surface 24 of the first electrode. The second insulating layer 40 has an opening 42 in which the first main surface 22 of the metal layer 20 is exposed from the second insulating layer 40, and the third insulating layer 50 includes the metal layer 20. The second main surface 24 has an opening 52 exposed from the third insulating layer 50.

(Base material part)
The base material part 10 has a function as a base material (core material) of the wiring board 1. As described above, the base material portion 10 includes the metal layer 20 formed in a pattern and the first insulating layer 30 disposed around the metal layer 20. Thereby, since the metal layer 20 itself forming the wiring circuit functions as a base material of the wiring substrate 1, it is not necessary to provide a base material between the wiring circuit on the front surface and the wiring circuit on the back surface. Therefore, the wiring board 1 can be thinned.

(Metal layer)
The metal layer 20 has a predetermined pattern shape and forms a wiring circuit of the wiring board 1. The material of the metal layer 20 is not particularly limited as long as it has conductivity. For example, the material of the metal layer 20 includes conductive metals such as copper, gold, silver, aluminum, tungsten, nickel, iron, and chromium. A particularly preferred material for the metal layer 20 is copper. By using copper as the material of the metal layer 20, the thermal conductivity of the wiring board 1 can be increased. Thereby, the heat generated from the electronic components mounted on the wiring board 1 can be efficiently radiated. Also, using copper as the material of the metal layer 20 is advantageous from the viewpoint of the price of the material and the availability. The pattern of the metal layer 20 is appropriately designed so as to be applied to the use of the wiring board or the manufacturing process thereof. The thickness of the metal layer 20 is not particularly limited and can be appropriately selected depending on the use of the wiring board 1. For example, the thickness of the metal layer 20 is preferably 3 to 150 μm, more preferably 5 to 100 μm, and still more preferably 10 to 50 μm.

  As shown in FIG. 2, the side surface 26 of the metal layer 20 preferably has a tapered shape from the first main surface 22 toward the second main surface 24. Thereby, when the base material part 10 is peeled from a base material for peeling described later in the method for manufacturing a wiring board described later, the metal layer 20 can be prevented from coming off from the base material part 10 due to the anchor effect of the metal layer 20. . For example, when the second insulating layer 40 is formed before the third insulating layer 50, the side surface 26 of the metal layer 20 has a cross-sectional area of the metal layer 20 in the plane direction of the wiring board 1 that is the second main surface. It is preferable to have a tapered shape that decreases toward 24.

(First insulating layer)
As described above, the first insulating layer 30 is disposed around the metal layer 20. Thereby, since the area | region demarcated by the side surface 26 of the metal layer 20 is filled with the 1st insulating layer 30, the intensity | strength of the base material part 10 can be made high. The material of the first insulating layer 30 is not particularly limited as long as it is an insulating material. However, since it can be easily disposed around the metal layer 20, the material of the first insulating layer 30 is preferably a cured product of a thermosetting resin composition and / or a cured product of an active energy ray curable resin composition. It is. The active energy ray-curable resin composition is a resin composition that is cured by irradiation with active energy rays. As active energy rays, ultraviolet rays, electron beams and the like are used.

  Examples of the thermosetting resin composition include an acrylate resin composition, a methacrylate resin composition, an epoxy resin composition, a phenol resin composition, a melamine resin composition, and a urea resin to which a thermal polymerization initiator is added. Examples thereof include resin compositions, unsaturated ester resin compositions, alkyd resin compositions, and urethane resin compositions. The active energy ray-curable resin composition includes an acrylate resin composition, a methacrylate resin composition, a urethane acrylate resin composition, an epoxy resin composition, and an epoxy acrylate resin composition. And ester acrylate resin compositions.

  Since it has the outstanding flexibility, the material of the especially preferable 1st insulating layer 30 is the hardened | cured material of the thermosetting and / or active energy ray hardening solder resist. The solder resist is a protective coating material that prevents unnecessary solder from adhering to the circuit surface during solder coating or component mounting. Further, the solder resist further has an insulator function as a permanent protection mask, which protects the circuit of the wiring board from humidity and dust and protects the circuit from electrical trouble. Examples of such a solder resist include PSR-9000 FLXFLX505E (manufactured by Taiyo Ink Co., Ltd.).

  The thickness of the first insulating layer is preferably the same as that of the metal layer 20.

(Second insulating layer)
As described above, the second insulating layer 40 covers the first main surface 22 of the metal layer 20. Thus, the second insulating layer 40 protects the metal layer 20 from the external environment such as dust, heat, and moisture. The material of the second insulating layer 40 is not particularly limited as long as it is an insulating material. However, since it can be easily applied to the first main surface 22 of the metal layer 20, the material of the second insulating layer 40 is preferably a cured product of a thermosetting resin composition and / or an active energy ray curable resin. It is a cured product of the composition. The material of the second insulating layer 40 is particularly preferably a cured product of a thermosetting and / or active energy ray curable solder resist because of its excellent flexibility. Examples of such a solder resist include PSR-9000 FLXFLX505E (manufactured by Taiyo Ink Co., Ltd.). The material of the second insulating layer 40 may be the same as or different from the material of the first insulating layer 30. However, since the first insulating layer 30 and the second insulating layer 40 can be formed simultaneously, the material of the second insulating layer 40 is preferably the same as the material of the first insulating layer 30.

  When a cured product of a thermosetting and / or active energy ray curable solder resist is used as the material of the first insulating layer 30 and the material of the second insulating layer 40, the solder resist protects the metal layer 20. In addition to the role of serving as a base material, the wiring board 1 can be further reduced in thickness.

(Third insulating layer)
As described above, the third insulating layer 50 covers the second main surface 24 of the metal layer 20. Thus, the third insulating layer 50 protects the metal layer 20 from the external environment such as dust, heat, and moisture. The material of the third insulating layer 50 is not particularly limited as long as it is an insulating material. However, since it can be easily applied to the second main surface 24 of the metal layer 20, the material of the third insulating layer 50 is preferably a cured product of a thermosetting resin composition and / or an active energy ray curable resin. It is a cured product of the composition. Since it has excellent flexibility, the material of the third insulating layer 50 is particularly preferably a cured product of a thermosetting and / or active energy ray curable solder resist. Examples of such a solder resist include PSR-9000 FLXFLX505E (manufactured by Taiyo Ink Co., Ltd.). The material of the third insulating layer 50 may be the same as or different from the material of the first insulating layer 30.

(Aperture)
As described above, the opening 42 is a portion where the first main surface 22 of the metal layer 20 is exposed from the second insulating layer 40, and the opening 52 is the second main surface of the metal layer 20. Reference numeral 24 denotes a portion exposed from the third insulating layer 50. That is, a part of the first main surface 22 of the metal layer 20 is exposed from the second insulating layer 40, and a part of the second main surface 24 of the metal layer 20 is exposed from the third insulating layer 50. doing. Thereby, the front side and the back side of the wiring board 1 can be electrically connected without performing drilling or plating. Therefore, it is possible to provide a thin wiring board having excellent productivity and low manufacturing cost.

  When there is no need to electrically connect the front side and the back side of the wiring board 1, the entire first main surface 22 of the metal layer 20 is covered with the second insulating layer 40 to form the second insulating layer 40. The opening 42 may not be formed, or the entire second main surface 24 of the metal layer 20 may be covered with the third insulating layer 50 and the opening 52 may not be formed in the third insulating layer 50. Good. When the metal layer 20 and the external wiring are electrically connected on the side surface of the wiring substrate 1, the entire first main surface 22 of the metal layer 20 is covered with the second insulating layer 40 and the second insulating layer. The opening 42 is not formed in 40, and the entire second main surface 24 of the metal layer 20 may be covered with the third insulating layer 50, and the opening 52 may not be formed in the third insulating layer 50. .

  The surface of the metal layer 20 exposed from the openings 42 and 52 may be covered with a metal plating film. Thereby, the electrical connectivity between the surface of the metal layer 20 exposed from the openings 42 and 52 and the external wiring can be further improved. Further, the surface of the metal layer 20 exposed from the openings 42 and 52 is protected from the external environment by the metal plating film. From the viewpoint of connectivity and electrical conductivity, preferred metal plating is tin plating or plating in which nickel and gold are combined. Further, instead of gold, silver or palladium can be used in combination with nickel. Further, instead of forming the metal plating film, a metal paste may be applied by a printing method.

  Next, with reference to FIG. 3, the manufacturing method of the wiring board in one Embodiment of this invention is demonstrated. FIG. 3 is a diagram for explaining a method of manufacturing a wiring board in one embodiment of the present invention.

  In one embodiment of the present invention, a method of manufacturing a wiring board includes a step of preparing a conductive substrate whose surface is covered with an insulating layer having an opening (step (A)), and a metal layer on the opening by plating. Forming step (Step (B)), having a pressure-sensitive adhesive layer on one side and preparing a flexible peeling substrate (Step (C)), peeling layer adhesive layer The first uncured insulating layer is formed on the peeling substrate so that the metal layer is embedded (step (D)) in which the conductive layer is adhered to the metal layer and the conductive substrate is peeled from the metal layer. Process (process (E)), process of curing the first uncured insulating layer (process (F)), process of separating the peeling substrate from the metal layer and the cured first uncured insulating layer (process) (G)), forming a second uncured insulating layer on the release surface of the metal layer and the cured first uncured insulating layer Comprising the step (H)), and a second step of curing the uncured insulating layer (step (I)). Hereafter, each process is demonstrated in detail with reference to FIG. 3 and FIG.

[Step (A)]
In step (A), as shown in FIG. 3A, a conductive substrate 110 whose surface is covered with an insulating layer 112 having an opening 114 is prepared.

(Conductive substrate)
The conductive substrate 110 is a substrate that forms a metal layer on the surface of the opening 114 of the insulating layer 112 by plating. The material of the conductive substrate 110 is not particularly limited as long as it has sufficient conductivity to form a metal layer on the surface by an electrolytic plating method. For example, a metal may be used for the material of the conductive substrate 110. In a later step, since the peeling substrate described later is peeled from the metal layer formed on the surface of the conductive substrate 110, the material of the conductive substrate 110 is preferably a metal layer formed by a plating method. It is a material that has low adhesion and can be easily peeled off from a metal layer formed by plating. From such a viewpoint, preferable materials for the conductive substrate 110 include stainless steel, chromium-plated cast iron, chromium-plated steel, titanium, titanium-lined material, nickel, and the like. Furthermore, it is particularly preferable to coat the surface of the conductive substrate 110 with a conductive inorganic material.

  The shape of the conductive substrate 110 may be a plate shape. However, the shape of the conductive substrate is not limited to a plate shape, and may be a sheet shape, a roll shape, a hoop shape, or the like. Alternatively, a sheet-shaped or plate-shaped conductive substrate may be attached to a rotating body (roll) to form a roll-shaped conductive substrate. In this case, it is preferable that a rotating body having conductivity is used, and the rotating body and the conductive substrate are easily conducted. When the conductive substrate has a hoop shape, a configuration in which two to several rotating bodies are installed inside the hoop-shaped conductive substrate can be considered. When the conductive substrate has a roll shape or a hoop shape, a metal layer formed by a plating method can be continuously produced. For this reason, compared with the case where a conductive base material is a sheet shape or plate shape, when a conductive base material is a roll shape or a hoop shape, the production efficiency of the metal layer formed by the plating method becomes high. From this point, the conductive substrate preferably has a roll shape or a hoop shape.

(Insulating layer)
The insulating layer 112 covers the conductive substrate 110, thereby preventing a metal layer from being formed on the surface of the coated conductive substrate 110. Thereby, a metal layer can be formed in a predetermined pattern. The material of the insulating layer 112 is not particularly limited as long as the material has an insulating property that can prevent the metal layer from being formed by an electrolytic plating method. For example, the material of the insulating layer 112 includes inorganic materials such as Al ₂ O ₃ and SiO ₂ and carbon thin films similar to diamond, so-called diamond-like carbon (DLC). A preferred material for the insulating layer 112 is diamond-like carbon because of its excellent durability and chemical resistance.

  The thickness of the insulating layer 112 corresponds to the depth of the opening 114. The depth of the opening 114 is related to the thickness of the metal layer to be formed. Therefore, the thickness of the insulating layer 112 is appropriately selected according to the thickness of the metal layer to be formed. For example, the thickness of the insulating layer 112 is preferably 0.1 to 100 μm, more preferably 0.5 to 10 μm, and still more preferably 1 to 7 μm. When the thickness of the insulating layer 112 is 0.1 μm or more, generation of pinholes in the insulating layer 112 can be suppressed. On the other hand, when the thickness of the insulating layer 112 is 100 μm or less, the formation time of the insulating layer 112 can be shortened, so that the manufacturing cost of the wiring board can be reduced.

(Aperture)
The metal layer is formed on the surface of the conductive substrate 110 in the opening 114 of the insulating layer 112 by plating. Therefore, the opening 114 has a pattern shape corresponding to the pattern of the metal layer 20 of the wiring board 1. The side surface of the opening 114 is preferably tapered so that the area of the opening increases as the distance from the conductive substrate 110 increases. Thereby, the electroconductive base material 110 can be easily peeled in a subsequent process from the metal layer formed on the surface of the electroconductive base material 110 in the opening 114 of the insulating layer 112. For example, the opening 114 having such a shape is formed by (a) forming a removable convex pattern on the surface of the conductive substrate, and (b) conductive having the removable convex pattern formed thereon. It can be formed by a step of forming an insulating layer on the surface of the conductive substrate and (c) a step of removing the convex pattern to which the insulating layer is attached (see, for example, JP-A-2008-305703).

(A) Step of forming a removable convex pattern on the surface of the conductive substrate In this step, a photolithographic method is used. Specifically, a photosensitive resist layer is formed on a conductive substrate, the photosensitive resist layer is exposed through a mask corresponding to the pattern shape of the metal layer of the wiring board, and the exposed photosensitive resist layer is developed. To do. The developed photosensitive resist layer becomes a convex pattern that can be removed. In addition, a photosensitive resist layer is formed on a conductive substrate, a portion of the photosensitive resist layer corresponding to the pattern shape of the metal layer of the wiring board is irradiated with laser light, and the photosensitive resist after irradiation with laser light is irradiated. A removable convex pattern may be formed by developing the layer.

(B) Step of forming an insulating layer on the surface of the conductive substrate on which the removable convex pattern is formed In this step, when forming a DLC thin film as the insulating layer, a vacuum deposition method, a sputtering method, an ion plate Conductive base material on which a removable convex pattern is formed by a dry coating method such as a physical vapor deposition method such as a coating method, an arc discharge method or an ionized vapor deposition method, or a chemical vapor deposition method such as a plasma CVD method An insulating layer can be formed on the surface. When an inorganic material such as Al ₂ O ₃ or SiO ₂ is formed as an insulating layer, it is removed by a physical vapor deposition method such as sputtering or ion plating, or a chemical vapor deposition method such as plasma CVD. An insulating layer can be formed on the surface of the conductive substrate on which possible convex patterns are formed.

(C) The process of removing the convex pattern which the insulating layer has adhered In this process, the photosensitive resist layer which is a convex pattern is used using a commercially available resist stripping solution, inorganic, organic alkali, organic solvent, etc. Remove. When the convex pattern is removed, the insulating layer attached to the surface of the convex pattern is also removed. Thereby, the opening 114 of the insulating layer 112 is formed in the portion where the convex pattern has been formed.

[Step (B)]
In step (B), as shown in FIG. 3B, a metal layer 116 is formed in the opening 114 by plating.

(Plating method)
A well-known method can be employ | adopted for the plating method in the manufacturing method of the wiring board in one Embodiment of this invention. For example, the plating method includes an electrolytic plating method and an electroless plating method. A preferred plating method is an electrolytic plating method.

(Electrolytic plating method)
Examples of the electrolytic bath for electrolytic plating include a copper sulfate bath, a copper borofluoride bath, a copper pyrophosphate bath, and a copper cyanide bath. If a stress relaxation agent such as an organic substance (also having a function as a brightener) is added to the electrolytic bath for electrolytic plating, the variation in electrodeposition stress can be further reduced.

  In the case of the electrolytic nickel plating method, a Watt bath, a sulfamic acid bath, or the like can be used as the electrolytic bath. In order to adjust the flexibility of the formed nickel layer, additives such as saccharin, paratoluenesulfonamide, sodium benzenesulfonate, and sodium naphthalenetrisulfonate may be added to these baths as necessary. Furthermore, in the case of the electrolytic gold plating method, an alloy plating method using potassium gold cyanide, a pure gold plating method using an ammonium citrate bath or a potassium citrate bath, or the like can be used. In the case of the alloy plating method, a metal layer of a binary alloy such as gold-copper, gold-silver, gold-cobalt, or a ternary alloy such as gold-copper-silver is formed. Similarly, other known methods can be used for plating other metals.

(Electroless plating method)
Examples of the electroless plating method include a copper plating method, a nickel plating method, a tin plating method, a gold plating method, a silver plating method, a cobalt plating method, and an iron plating method. In the electroless plating method used industrially, a reducing agent is added to the plating solution, and electrons generated by the oxidation reaction are used for the deposition reaction of the metal layer. The plating solution contains a metal salt, a complexing agent, a reducing agent, a pH adjusting agent, a pH buffer material, a stabilizer, and the like. In the electroless copper plating method, for example, copper sulfate is used as a metal salt, formalin is used as a reducing agent, and Rossel salt or ethylenediaminetetraacetic acid (EDTA) is used as a complexing agent. Further, the pH of the plating solution is mainly adjusted with sodium hydroxide, but may be adjusted with potassium hydroxide, lithium hydroxide, or the like. Carbonates and phosphates are used as buffering agents for the plating solution. As a plating solution stabilizer, cyanide, thiourea, bipyridyl, O-phenanthroline, neocuproine, or the like that is preferentially complexed with monovalent copper is used.

  In the case of the electroless nickel plating method, for example, nickel sulfate is used as a metal salt, and sodium hypophosphite, hydrazine, a borohydride compound, or the like is used as a reducing agent. When sodium hypophosphite is used as the reducing agent, phosphorus is contained in the formed metal layer, and the corrosion resistance and wear resistance of the formed metal layer can be improved. Moreover, a monocarboxylic acid or its alkali metal salt can be used as a buffering agent. What forms a stable soluble complex with nickel ions in the plating solution is used as a complexing agent. For example, complexing agents include acetic acid, lactic acid, tartaric acid, malic acid, citric acid, glycine, alanine, EDTA and the like. Sulfur compounds and lead ions are used as stabilizers.

  The electroless plating that can be used in the present invention is, for example, immersed in an electroless copper plating solution at a temperature of about 60 to 90 ° C. after a palladium catalyst is attached to the surface of the electroconductive substrate for plating as necessary. This is a method of performing copper plating. In electroless plating, the substrate is not necessarily conductive. However, when anodizing the substrate, the substrate needs to be conductive. In particular, when the material of the conductive substrate is Ni, electroless plating includes a method in which the surface is anodized and then immersed in an electroless copper plating solution to form copper.

(Metal layer formed in the opening)
Examples of the metal layer 116 formed in the opening 114 include a metal layer of a metal having conductivity such as silver, copper, gold, aluminum, tungsten, nickel, iron, and chromium. The metal layer 116 formed in the opening 114 desirably includes one or more metals having a volume resistivity (specific resistance) at 20 ° C. of 20 μΩ / cm or less. In view of the price of the metal and the availability of the metal, the metal of the metal layer to be formed is particularly preferably copper. Further, the metal of the metal layer to be formed may be a single metal, or may be an alloy of two or more kinds of metals in order to impart functionality. Further, as long as the volume resistivity of the metal layer to be formed does not become too high, the metal layer to be formed may contain a metal oxide. However, it is preferable that a metal having a volume resistivity of 20 μΩ / cm or less is most contained as a component in the metal layer to be formed.

  The thickness (plating thickness) of the metal layer 116 formed on the surface of the conductive substrate 110 is not particularly limited as long as the metal layer 116 to be formed has sufficient conductivity. For example, the thickness of the metal layer 116 formed on the surface of the conductive substrate 110 is preferably 3 to 150 μm, more preferably 5 to 100 μm, and further preferably 10 to 50 μm. When the thickness of the metal layer 116 is 3 μm or more, sufficient adhesion strength between the metal layer and the first insulating layer can be obtained in the wiring board. On the other hand, when the thickness of the metal layer 116 is 150 μm or less, the metal layer 116 having a desired thickness can be formed in a short time, and the manufacturing cost of the wiring board can be reduced.

  It is preferable to form the metal layer 116 in the opening 114 so that the cross-sectional area in the planar direction of the conductive substrate 110 decreases as the distance from the insulating layer 112 increases. Thereby, in the process (G) of peeling the base material for peeling from the metal layer and the cured first uncured insulating layer, which will be described later, from the cured first uncured insulating layer due to the anchor effect of the metal layer 116. It is possible to suppress the metal layer 116 from coming off. In order to form the metal layer 116 in this manner, the metal layer 116 is preferably thicker than the insulating layer 112.

[Step (C)]
In step (C), as shown in FIG. 3 (c), a peeling substrate 120 having a pressure-sensitive adhesive layer 122 on one surface and having flexibility is prepared. Since the peeling substrate 120 has flexibility, the peeling substrate can be easily peeled from the metal layer and the cured first uncured insulating layer in the step (G) described later.

(Peeling substrate)
The peeling substrate 120 adheres to the formed metal layer 116 via the adhesive layer 122. As a result, the metal layer 116 is peeled from the conductive substrate 110. The material of the peeling substrate 120 is not particularly limited as long as it has mechanical strength to withstand the stress generated at this time and has flexibility. For example, the material of the peeling substrate 120 includes glass, plastic, metal, and the like.

  Examples of the glass include soda glass, alkali-free glass, and tempered glass.

  Examples of the plastic include polystyrene resin, acrylic resin, polymethyl methacrylate resin, polycarbonate resin, polyvinyl chloride resin, polyvinylidene chloride resin, polyethylene resin, polypropylene resin, polyimide resin, polyamide resin, polyamideimide resin, and polyetherimide resin. , Polyether ether ketone resin, polyarylate resin, polyacetal resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyethylene naphthalate resin and other thermoplastic polyester resins, cellulose acetate resin, fluororesin, polysulfone resin, polyethersulfone resin, poly Thermoplastic resins such as methylpentene resin, polyurethane resin, diallyl phthalate resin, epoxy resin, phenol resin, melamine resin, Such as a thermosetting resin such as fluororesin and the like.

  Examples of the metal include metals such as copper, aluminum, stainless steel, nickel, iron, titanium, and alloys thereof (for example, 42 alloy). Preferred metals include stainless steels (SUS) such as austenitic stainless steel, ferritic stainless steel and martensitic stainless steel. When the metal of the metal layer formed by plating is copper, the linear thermal expansion coefficient of SUS304, which is an austenitic stainless steel, is almost the same as the linear thermal expansion coefficient of copper. SUS304 is preferred. When the linear expansion coefficient of the peeling substrate 120 is equal to the linear thermal expansion coefficient of the metal layer formed by the plating method, the metal layer formed by the plating method is distorted even if the metal layer receives a thermal history. This is because there are fewer.

  The thickness of the peeling substrate 120 is not particularly limited as long as the peeling substrate 120 has flexibility. For example, the thickness of the peeling substrate 120 is preferably 10 μm to 1 mm, and more preferably 20 μm to 0.5 mm. When the substrate 120 for peeling is 10 μm or more in thickness, when the wiring board is manufactured by a roll-to-roll method, the peeling substrate 120 is adhered by adhering a metal layer formed by a plating method. This is advantageous because the working substrate 120 can be transported between processes. On the other hand, when the thickness of the peeling substrate 120 is 1 mm or less, curling is unlikely to occur in the peeling substrate 120, and when the peeling substrate after the predetermined process is wound up and collected as a scroll, peeling The base material 120 is less likely to be curled.

The linear thermal expansion coefficient at 20 to 200 ° C. of the peeling substrate 120 is preferably close to the linear thermal expansion coefficient at 20 to 200 ° C. of the metal layer 116 formed by plating. For example, the linear thermal expansion coefficient at 20 to 200 ° C. of the peeling substrate 120 is preferably 3.0 × 10 ⁻⁵ / K or less, more preferably 2.5 × 10 ⁻⁵ / K or less. More preferably, it is 2.0 × 10 ⁻⁵ / K or less.

(Adhesive layer)
The pressure-sensitive adhesive layer 122 needs to have appropriate adhesion and peelability to the metal layer 116 formed by plating. In the later-described step (D), the metal layer 116 formed by the plating method adheres to the adhesive layer 122, but in the later-described step (G), the metal layer 116 formed by the plating method is peeled off from the adhesive layer 122. Because. Moreover, in order to suppress that the adhesive layer 122 peels from the base material 120 for peeling in the below-mentioned process (G), the adhesive layer 122 has strong adhesiveness with respect to the base material 120 for peeling. Preferably it is. Instead of providing the pressure-sensitive adhesive layer, the material constituting the peeling substrate 120 may have the necessary adhesiveness.

  As a material used for the pressure-sensitive adhesive layer 122, a thermoplastic resin composition, a thermosetting resin composition, an active energy ray curable resin composition, or the like can be used. Moreover, the active energy ray-curable resin composition can be cured by combining active energy rays and heat. The weight average molecular weight of the thermoplastic resin composition, the thermosetting resin composition, and the active energy ray curable resin composition is preferably 500 or more. This is because when the molecular weight of these resin compositions is 500 or more, sufficient cohesive force of the resin composition is ensured, and sufficient adhesion between the pressure-sensitive adhesive layer 122 and the metal layer 116 is obtained.

  Examples of the thermoplastic resin composition used for the pressure-sensitive adhesive layer 122 include natural rubber, polyisoprene, poly-1,2-butadiene, polyisobutene, polybutene, poly-2-heptyl-1,3-butadiene, and poly-2- (Di) enes such as t-butyl-1,3-butadiene and poly-1,3-butadiene; polyethers such as polyoxyethylene, polyoxypropylene, polyvinyl ethyl ether, polyvinyl hexyl ether and polyvinyl butyl ether; polyvinyl Polyesters such as acetate and polyvinyl propionate; polyurethane; ethyl cellulose; polyvinyl chloride; poly (meth) acrylonitrile; polysulfone; polysulfide; phenoxy resin; polymethyl (meth) acrylate, polyethyl (meth) acrylate, polyisopro (Meth) acrylate, polybutyl (meth) acrylate, poly-t-butyl (meth) acrylate, poly-2-ethylhexyl (meth) acrylate, poly-3-ethoxypropyl (meth) acrylate, polyoxycarbonyltetra (meth) Acrylate, polydodecyl (meth) acrylate, polytetradecyl (meth) acrylate, poly-n-propyl (meth) acrylate, poly-3,3,5-trimethylcyclohexyl (meth) acrylate, poly-2-nitro-2-methyl Examples thereof include poly (meth) acrylic acid esters such as propyl (meth) acrylate and poly-1,1-diethylpropyl (meth) acrylate. The monomers constituting these polymers may be used as a copolymer obtained by copolymerization of two or more kinds, if necessary, or may be used by blending two or more kinds of the above polymers or copolymers. .

  Examples of the thermosetting resin composition used for the pressure-sensitive adhesive layer 122 include natural rubber, isoprene rubber, chloroprene rubber, polyisobutylene, butyl rubber, halogenated butyl, acrylonitrile-butadiene rubber, styrene-butadiene rubber, polyisobutene, carboxy rubber, Examples include a combination of a resin composition such as neoprene and polybutadiene and a crosslinking agent. Examples of the crosslinking agent include sulfur, aniline formaldehyde resin, urea formaldehyde resin, phenol formaldehyde resin, ligrin resin, xylene formaldehyde resin, melamine formaldehyde resin, epoxy resin, urea resin, aniline resin, melamine resin, phenol resin, formalin resin, Examples thereof include metal oxides, metal chlorides, oximes, and alkylphenol resins. In addition, you may add additives, such as a general purpose vulcanization accelerator, to a thermosetting resin composition in order to increase a crosslinking reaction rate.

  Other thermosetting resin compositions include those that use a curing agent. Examples of the thermosetting resin composition include a resin composition having a functional group such as a carboxyl group, a hydroxyl group, an epoxy group, an amino group, and an unsaturated hydrocarbon group. Examples of the curing agent include a curing agent having a functional group such as epoxy group, hydroxyl group, amino group, amide group, carboxyl group, and thiol group, or metal chloride, isocyanate, acid anhydride, metal oxide, peroxide. And the like. For the purpose of increasing the curing reaction rate, additives such as general-purpose catalysts can be used in the thermosetting resin composition. Specifically, specific examples of the thermosetting resin composition include a curable acrylic resin composition, an unsaturated polyester resin composition, a diallyl phthalate resin composition, an epoxy resin composition, a polyurethane resin composition, and the like. Can be mentioned.

  The active energy ray-curable resin composition used for the pressure-sensitive adhesive layer 122 includes, for example, an acrylic resin composition, an epoxy resin composition, a polyester resin composition, a urethane resin composition, and the like as a base polymer, each of which is radically polymerizable or Examples thereof include a resin composition provided with a cationically polymerizable functional group. Examples of the radical polymerizable functional group include a carbon-carbon double bond such as an acryl group (acryloyl group), a methacryl group (methacryloyl group), a vinyl group, and an allyl group. Among these, preferable radical polymerizable functional group reactivity is a good acrylic group (acryloyl group). The cationically polymerizable functional group includes an epoxy group (glycidyl ether group, glycidylamine group) and the like, and a preferable cationically polymerizable functional group is a highly reactive alicyclic epoxy group. Specific examples of the active energy ray-curable resin composition include acrylic urethane, epoxy (meth) acrylate, epoxy-modified polybutadiene, epoxy-modified polyester, polybutadiene (meth) acrylate, and acrylic-modified polyester.

  Additives such as cross-linking agents, curing agents, diluents, plasticizers, antioxidants, fillers, colorants, UV absorbers and tackifiers are added to the adhesive of the adhesive layer 122 as necessary. May be.

  As a method of forming the pressure-sensitive adhesive layer 122 on the peeling substrate 120, a method of applying a pressure-sensitive adhesive to the peeling substrate 120 is preferable because it is easy to manufacture. Examples of the method for applying the adhesive include a die coating method, a roll coating method, a reverse roll coating method, a gravure coating method, a bar coating method, and a comma coating method.

  The thickness of the pressure-sensitive adhesive layer 122 is preferably 0.5 to 100 μm, more preferably 3 to 30 μm, and still more preferably 5 to 20 μm. When the thickness of the pressure-sensitive adhesive layer 122 is 0.5 μm or more, the pressure-sensitive adhesive layer 122 has sufficient adhesion to the metal layer 116. On the other hand, when the thickness of the pressure-sensitive adhesive layer 122 is 100 μm or less, the adhesion does not become too high, and the metal layer 116 can be appropriately peeled from the pressure-sensitive adhesive layer 122.

The linear expansion coefficient at 20 to 200 ° C. of the pressure-sensitive adhesive layer 122 (the pressure-sensitive adhesive layer after curing when a curable resin composition is used) is preferably 3.0 × 10 ⁻⁵ / K or less. More preferably, it is 2.5 × 10 ⁻⁵ / K or less, and further preferably 2.0 × 10 ⁻⁵ / K or less. The linear expansion coefficient of the pressure-sensitive adhesive layer 122 at 20 to 200 ° C. is particularly preferably equal to or substantially equal to the linear expansion coefficient of the metal constituting the metal layer 166.

[Step (D)]
In step (D), as shown in FIGS. 3 (e) and 3 (f), the adhesive layer 122 of the peeling substrate 120 is adhered to the metal layer 116, and the conductive substrate 110 is peeled from the metal layer 116. .

  Specifically, the surface of the conductive substrate 110 on which the metal layer 116 is formed and the surface of the substrate 120 for peeling on which the pressure-sensitive adhesive layer 122 is provided face each other so that the surface of the peeling substrate 120 and the conductive substrate 110 are electrically conductive. Then, the conductive substrate 110 is peeled off from the peeling substrate 120. As a result, the metal layer 116 sticks to the pressure-sensitive adhesive layer 122 of the peeling substrate 120 and leaves the conductive substrate 110. That is, the metal layer 116 of the conductive substrate 110 is transferred to the peeling substrate 120.

[Step (E)]
In the step (E), as shown in FIG. 4A, the first uncured insulating layer 130 is formed on the peeling substrate 120 so that the metal layer 116 is embedded. Examples of the method for forming the first uncured insulating layer 130 include a method of applying a curable resin composition and a method of laminating a sheet of the curable resin composition. Examples of the method for applying the curable resin composition include a screen printing method, a die coating method, a roll coating method, a reverse roll coating method, a gravure coating method, a bar coating method, and a comma coating method. The material of the first uncured insulating layer 130 is the thermosetting resin composition and / or the active energy ray curable resin composition used for the first insulating layer 30 and the second insulating layer 40 (see FIG. 2). Preferably, it is a thermosetting and / or active energy ray curable solder resist.

  The first uncured insulating layer 130 may be formed on the peeling substrate 120 so that a part of the metal layer 116 is exposed by a screen printing method or the like. As a result, electrode pads for connecting to external wiring or mounting electronic components can be formed without using a photolithographic method or the like.

[Step (F)]
In the step (F), the first uncured insulating layer 130 is cured to form a first cured insulating layer. For example, the first uncured insulation layer 130 is cured by heating the first uncured insulation layer 130 or irradiating the first uncured insulation layer 130 with active energy rays. An insulating layer is formed. Thereby, the 1st insulating layer 30 and the 2nd insulating layer 40 of the wiring board 1 are formed (refer FIG. 2).

  In the step (F), the first uncured insulating layer 130 was cured by photolithography, except for a part of the first uncured insulating layer 130 covering the metal layer 116, and was not cured by development. The first uncured insulating layer 130 may be removed. Thereby, the electrode pad for connecting with external wiring or mounting an electronic component can be formed.

  For example, when the first uncured insulating layer 130 is cured using active energy rays, a negative film or the like is used to mask a portion where the metal layer 116 is not desired to be covered with the first uncured insulating layer 130. To do. Thereby, even if the active energy ray is irradiated to the first uncured insulating layer 130, the masked portion of the first uncured insulating layer 130 is not cured. Then, after irradiating the first uncured insulating layer 130 with active energy rays, the uncured first uncured insulating layer 130 is removed. Thereby, the metal layer 116 can be exposed from the first cured insulating layer, and an electrode pad or the like can be formed.

[Step (G)]
In the step (G), as shown in FIG. 4B, the peeling substrate 120 is peeled from the metal layer 116 and the first cured insulating layer 132. At this time, it is preferable that the pressure-sensitive adhesive layer 122 provided on the peeling substrate 120 does not remain on the peeling surface of the metal layer 116 and the first cured insulating layer 132.

[Step (H)]
In the step (H), as shown in FIG. 4C, the second uncured insulating layer 140 is formed on the peeling surface of the metal layer 116 and the first cured insulating layer 132. Examples of the method of forming the second uncured insulating layer 140 include a method of applying a curable resin composition and a method of laminating a sheet of the curable resin composition. Examples of the method for applying the curable resin composition include a screen printing method, a die coating method, a roll coating method, a reverse roll coating method, a gravure coating method, a bar coating method, and a comma coating method. The material of the second uncured insulating layer 140 is the thermosetting resin composition and / or the active energy ray curable resin composition used for the third insulating layer 50 (see FIG. 2). It is a thermosetting and / or active energy ray curable solder resist.

  The second uncured insulating layer 140 may be formed on the separation surface of the metal layer 116 and the first cured insulating layer 132 so that a part of the metal layer 116 is exposed by a screen printing method or the like. . As a result, electrode pads for connecting to external wiring or mounting electronic components can be formed without using a photolithographic method or the like. In addition, when a part of the metal layer 116 is exposed from the first cured insulating layer 132, the front and back surfaces of the wiring board can be electrically connected.

[Step (I)]
In the step (I), the second uncured insulating layer 140 is cured to form a second cured insulating layer. For example, the second uncured insulation layer 140 is cured by heating the second uncured insulation layer 140 or irradiating the second uncured insulation layer 140 with active energy rays. An insulating layer is formed. Thereby, the third insulating layer 50 of the wiring substrate 1 is formed.

  In this step, the second uncured insulating layer 140 is cured by photolithography, except for a part of the second uncured insulating layer 130 covering 116, and the second uncured uncured layer that has not been cured by development. The cured insulating layer 140 may be removed. Thereby, the electrode pad for connecting with external wiring or mounting an electronic component can be formed. Further, when a part of the metal layer 116 is exposed from the first cured insulating layer 132, the front surface and the back surface of the wiring board can be electrically connected.

  For example, when the second uncured insulating layer 140 is cured using active energy rays, a negative film or the like is used to mask a portion where the metal layer 116 is not desired to be covered by the second uncured insulating layer 140. To do. Thereby, even if the active energy ray is irradiated to the second uncured insulating layer 140, the masked portion of the second uncured insulating layer 140 is not cured. Then, after irradiating the second uncured insulating layer 140 with active energy rays, the uncured second uncured insulating layer 140 is removed. Thereby, the metal layer 116 can be exposed from the cured product of the second uncured insulating layer 140, and an electrode pad or the like can be formed.

[Other processes]
[Plating process]
When forming an electrode pad on the wiring board, a plating step may be performed after step (I) in order to cover the surface of the electrode pad with a metal plating film. Thereby, the electrode pad is easily connected to the external wiring. A preferable metal plating is tin plating or plating in which nickel and gold are combined. Further, instead of gold, silver or palladium can be used in combination with nickel. In addition, examples of the plating method performed in the plating process include an electrolytic plating method and an electroless plating method.

[Solder paste application process]
When forming an electrode pad on a wiring board, a solder paste application step may be performed after step (I) in order to coat the surface of the electrode pad with solder. Thereby, the electrode pad is easily connected to the external wiring. Examples of the application method performed in the solder paste application process include a solder paste printing method and an electric solder plating method.

[Cutting process]
When an assembly of wiring boards is manufactured by the step (I), the cutting process is performed after the step (I) in order to cut and separate the aggregates after the step (I) to manufacture the wiring substrate. May be implemented. Examples of the cutting method performed in the cutting process include a diamond blade dicing method.

[Modification]
In the method for manufacturing a wiring board according to one embodiment of the present invention described above, the step of preparing a conductive substrate whose surface is covered with an insulating layer having an opening (step (A)), the plating is performed on the opening. A step of forming a metal layer (step (B)), a step of having a pressure-sensitive adhesive layer on one side and preparing a flexible peeling base material (step (C)), and sticking of the peeling base material The step of adhering the agent layer to the metal layer and peeling the conductive substrate from the metal layer (step (D)) may be performed by a roll-to-roll method. Hereafter, with reference to FIG. 4, the process of implementing process (A)-(D) by the roll-to-roll method is demonstrated. In this step, a rotating body (roll) 210 is used as the conductive substrate. Then, using the rotating body 210, the peeling substrate 220 to which the metal layer 216 is adhered is obtained as a scroll while continuously peeling the rotating body 210 from the metal layer 216 formed by the electrolytic plating method. Drawing 5 is a figure for explaining the process of carrying out process (A)-(D) by roll to roll method.

  The surface of the rotating body 210 is covered with an insulating layer having an opening (not shown). The rotating body 210 is preferably made of metal. Furthermore, it is preferable to use a drum electrode or the like used in the drum electrolytic deposition method as the rotating body 210. The material forming the surface of the rotating body 210 is preferably a material with relatively low plating adhesion such as stainless steel, chrome-plated cast iron, chrome-plated steel, titanium, or titanium-lined material. By using a rotating body as the conductive base material, it is possible to continuously produce a peeling base material with a metal layer adhered thereto and obtain it as a scroll. For this reason, the productivity of the wiring board is remarkably increased. The lower half of the rotating body 210 is immersed in the plating solution 312 in the plating tank 310.

  In order to press the metal layer 216 formed on the rotating body 210 against the peeling substrate, a pressure-bonding roll 340 is provided on the upper side of the rotating body 210. The interval between the rotating body 210 and the pressure-bonding roll 340 is appropriately selected depending on the pressure applied.

  When the peeling base material 220 to which the metal layer 216 is adhered is recovered as the scroll 330, the metal layer 216 of the peeling base material 220 is adhered to prevent the metal layer 216 from being peeled from the peeling base material 220. You may affix the cover film 352 which consists of a photocurable resin composition on the surface which has it. The cover film 352 is supplied from the roll 350. In addition, a UV (ultraviolet) irradiation device 360 is provided to cure the cover film attached to the peeling substrate 220. The steps of carrying out steps (A) to (D) by the roll-to-roll method are carried out as follows.

[Step (A)]
In the step (A), a rotating body 210 whose surface is covered with an insulating layer having an opening is prepared.

[Step (B)]
In step (B), when a voltage is applied between an anode (not shown) and the rotating body 210 and the rotating body 210 is rotated at a constant speed, a metal layer is formed in the opening of the insulating layer (not shown) on the surface of the rotating body 210. 216 forms.

[Step (C)]
In the step (C), a peeling substrate 220 having a pressure-sensitive adhesive layer (not shown) is prepared as a scroll 320. The peeling substrate 220 is supplied from the scroll 320.

[Step (D)]
In the step (D), by passing the peeling base material 220 supplied from the scroll 320 between the rotating body 210 and the pressure roll 340, the metal layer 216 is adhered to the adhesive layer (not shown), The rotating body 210 is peeled off from 216.

  In order to prevent the metal layer 216 adhered to the peeling substrate 220 from being peeled off, a cover film 352 may be attached to the surface of the peeling substrate 220 to which the metal layer 216 is adhered. Then, the cover film 352 may be cured by irradiating the cover film 352 with ultraviolet rays from the UV irradiation device 360. The cover film 352 is supplied from the roll 350.

  The peeling base material 220 to which the metal layer 216 is adhered is wound up, and the peeling base material 220 to which the metal layer 216 is adhered is collected as a scroll 330. The scroll 330 is then transported for the next step.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, an Example does not limit this invention.

[Example 1]
(Production of negative film)
A negative film of the test pattern of the metal layer was produced. The test pattern includes a unit composed of two electrode pads connected to the external wiring and one stripe line (opaque) connecting the two electrode pads. The pad size of the electrode pad was 6 mm × 4 mm. The width of the striped line was 2 mm and the length was 20 mm. The two units were arranged in parallel so that the distance between adjacent electrode pads was 1 mm. The two units arranged in parallel were arranged on a test piece having a size of 34 × 13 mm. Three sets of these were arranged in parallel, and a frame (opaque) having a width of 2 mm was formed around the periphery. Each electrode pad was connected to the frame by a line having a width of 0.1 mm.

(Formation of convex pattern)
A resist film (Photech RY3315, 15 μm thick, manufactured by Hitachi Chemical Co., Ltd.) was bonded to both surfaces of a 44 × 49 mm stainless steel plate (SUS316L, # 400 polished finish, thickness 500 μm, manufactured by Nisshin Steel Co., Ltd.). The bonding conditions were a roll temperature of 105 ° C., a pressure of 0.5 MPa, and a line speed of 1 m / min. Next, the negative film was allowed to stand on one side of a stainless plate (conductive substrate). Using a UV irradiation device, UV irradiation was performed at 250 mJ / cm ² from above the stainless steel plate on which the negative film was placed under a vacuum of 600 mmHg or less. Furthermore, it developed by 1% sodium carbonate aqueous solution, and the convex-shaped pattern (protrusion part; height 15 micrometers) was obtained. Note that the surface opposite to the surface on which the pattern is formed is not developed because it is exposed entirely, and a resist film is formed on the entire surface.

(Formation of insulating layer)
A DLC film was formed on a stainless steel plate using a PBII / D apparatus (Type III, manufactured by Kurita Seisakusho Co., Ltd.). A stainless steel plate with a resist film attached thereto was put in the chamber, the inside of the chamber was evacuated, and then the stainless steel plate surface was cleaned with argon gas. Next, hexamethyldisiloxane was introduced into the chamber, and an intermediate layer was formed on the stainless steel plate to a thickness of 0.1 μm. Subsequently, toluene, methane, and acetylene gas were introduce | transduced, and the DLC layer was formed on the intermediate | middle layer so that a film thickness might be set to 5-6 micrometers.

(Formation of opening (removal of convex pattern with insulating layer attached))
The stainless steel plate with the insulating layer adhered was immersed in an aqueous sodium hydroxide solution (10%, 50 ° C.) and left for 8 hours with occasional rocking. As a result, the resist film forming the convex pattern and the DLC film adhering thereto were peeled off. Since some of the convex patterns were difficult to peel off, all the convex patterns could be removed by lightly rubbing with a cloth. As a result, an opening was formed in the insulating layer on the stainless steel plate. The shape of the opening is wider toward the opening direction, and the inclination angle of the side surface of the opening is approximately 45 degrees. The depth of the opening was 5 to 6 μm. Moreover, the opening part was formed corresponding to the electrode pad, stripe line, and frame of the negative film. The size of the opening corresponding to the electrode pad was 6 mm × 4 mm, and the width of the opening corresponding to the stripe line and the frame was 2 mm.

(Copper plating)
An adhesive film (Hitalex K-3940B, manufactured by Hitachi Chemical Co., Ltd.) was attached to the surface (back surface) where the opening of the stainless steel plate was not formed. An electrolytic bath for electrolytic copper plating (copper sulfate (pentahydrate) 250 g / L, sulfuric acid 70 g / L, Cubelite AR (Hagiwara Eugelite) (Additional product, Inc.) 4ml / L aqueous solution, 30 ° C), current density is 10A / dm ² , and plating process is continued until the thickness of the metal layer formed on the stainless steel plate is about 35μm It was. A metal layer was formed in and over the opening of the insulating layer.

(Preparation of active energy ray-curable resin composition)
Formulation composition 1 described below was charged into a 500 cm ³ three-necked flask equipped with a thermometer, a cooling tube, and a nitrogen introduction tube. Then, the composition 1 is heated to 60 ° C. with gentle stirring to initiate polymerization, and stirred at reflux for 60 hours at 60 ° C. while bubbling with nitrogen, and has a hydroxyl group in the side chain. An acrylic resin was obtained. Thereafter, 5 parts by weight of Karenz MOI (2-isocyanatoethyl methacrylate; manufactured by Showa Denko KK) is added and reacted at 50 ° C. with gentle stirring, and a reactive polymer having a photopolymerizable functional group in the side chain. Solution 1 was obtained.

(Composition composition 1)
2-ethylhexyl methacrylate 70 parts by weight Butyl acrylate 15 parts by weight 2-hydroxyethyl methacrylate 10 parts by weight Acrylic acid 5 parts by weight Azobisisobutyronitrile 0.1 part by weight Toluene 60 parts by weight Ethyl acetate 60 parts by weight

  The obtained reactive polymer 1 had a methacryloyl group in the side chain, and the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography was 800,000.

  2-methyl-1 [4-methylthio] phenyl] -2-morpholinopropan-1-one (trade name Irgacure 907, Ciba Geigy (as a photopolymerization initiator) was added to 100 parts by weight (solid content) of the solution 1 of the reactive polymer. 1 part by weight), 3 parts by weight of an isocyanate-based cross-linking agent (trade name Coronate L-38ET, manufactured by Nippon Polyurethane Co., Ltd.), and 50 parts by weight of toluene are added to obtain an active energy ray-curable resin composition 1. Obtained.

(Preparation of substrate for peeling having adhesive layer)
The obtained resin composition 1 was applied to the surface of SUS304, which is a peeling substrate having a thickness of 50 μm and a 120 mm square, so that the film thickness after drying was 15 μm. And the adhesive layer which has ultraviolet curing property was formed, and it formed on the base material for peeling. The drying condition of the resin composition 1 was 10 minutes at 80 ° C.

(Metal layer transfer)
The peeling base material and the stainless steel plate were bonded using a roll laminator so that the surface of the peeling base material on which the pressure-sensitive adhesive layer was formed and the surface of the stainless steel plate that had been subjected to copper plating overlapped. Lamination conditions were a roll temperature of 30 ° C., a pressure of 0.3 MPa, and a line speed of 0.5 m / min. Subsequently, when the stainless steel plate bonded to the peeling base material was peeled off, the metal layer made of copper formed on the stainless steel plate was transferred to the adhesive layer of the peeling base material. Next, a 12 μm-thick PET film E-5100 (manufactured by Toyobo Co., Ltd.) is processed on the surface of the peeling substrate on which the metal layer is transferred at a roll temperature of 30 ° C., a pressure of 0.3 MPa, and a line speed of 0.5 m / min. Bonded with conditions. Further, the surface of the peeling substrate on which the metal layer was transferred was irradiated with ultraviolet rays at a dose of 1 J / cm ² .

  A part of the substrate for peeling onto which the metal layer was transferred was cut out, and the cross section was observed using a scanning electron micrograph (magnification 2000 times). The size of the metal layer corresponding to the electrode pad having a size of 6 mm × 4 mm was 6050 × 4050 μm. The width of the metal layer corresponding to the striped line having a width of 2 mm was 2050 μm. The width of the metal layer corresponding to the 2 mm wide frame was 2050 μm. The metal layer was buried in the adhesive layer at a depth of approximately 5 μm.

  100 test patterns were produced. In order to produce the test pattern, the plating process and the transfer process may be performed from the second sheet, and it is not necessary to perform patterning for each number of sheets. Therefore, the work for producing 100 test patterns was completed in a relatively short time. .

(Preparation of solder resist pattern)
In order to cover the edge of the metal layer with a solder resist, first, a photosensitive liquid solder resist (manufactured by Taiyo Ink Co., Ltd., trade name: PSR-9000 FLX505E) is screened on the entire surface of the peeling base material on which the metal layer is present. It was applied by printing and heat-treated at a temperature of 80 ° C. for 25 minutes. The thickness of the solder resist after provisional curing was 15 μm.

  Next, a mask was attached, the solder resist was exposed, and developed to remove unnecessary portions of the solder resist. The overlap amount of the solder resist with respect to the metal layer edge was 0.5 mm, and the opening size of the electrode pad connected to the external wiring was 5 × 3 mm. The other part of the metal layer was covered with the solder resist including stripe lines and frames. Thereafter, the solder resist was dried at a temperature of 150 ° C. for 60 minutes.

(Manufacture of wiring boards)
The base material for peeling was peeled from the metal layer and the solder resist. This peeling operation was easily performed. At this time, the pressure-sensitive adhesive layer remained on the peeling substrate (SUS substrate), and the pressure-sensitive adhesive layer did not remain on the metal layer and the solder resist. Next, in order to cover the metal layer on the release surface with a solder resist, a photosensitive liquid solder resist (manufactured by Taiyo Ink Co., Ltd., trade name: PSR-9000 FLX505E) is screen-printed on the entire surface where the metal layer on the release surface exists. It was applied and dried at a temperature of 80 ° C. for 25 minutes. The thickness of the solder resist after drying was 15 μm.

  Next, a mask was attached, the peeled surface was exposed, and developed to remove unnecessary portions of the solder resist. The overlap amount of the solder resist with respect to the metal layer edge was 0.5 mm, and the opening size of the electrode pad connected to the external wiring was 5 × 3 mm. The other part of the metal layer was covered with the solder resist including stripe lines and frames. Thereafter, the solder resist was dried at a temperature of 150 ° C. for 60 minutes.

  Next, a tin plating film having a thickness of 3 μm was formed on the portions where the front and back metal layers were exposed by an electroless plating method.

  The wiring board of Example 1 was obtained by cutting into a predetermined size (34 × 13 mm).

[Comparative Example 1]
A flexible substrate was prepared by laminating a 12 μm thick copper foil on both sides of a 100 μm thick polyimide film. Next, in order to electrically connect the front and back of the copper foil, a φ0.3 mm through hole was drilled at a predetermined position. A plated film was formed in the through hole so as to close the through hole by electrolytic copper plating. At the same time, plating was formed on the entire surface of the front and back copper foils.

  Next, after the photosensitive film 103 (Photech RY3237, 37 μm thickness, manufactured by Hitachi Chemical Co., Ltd.) was laminated as a protective film on the surface of the plating film, the same negative film as that used in the manufacture of Example 1 was formed on the upper part. A negative film was placed and exposed by irradiating with ultraviolet rays in the same manner as in Example 1. Then, the pattern of the photosensitive film corresponding to the electrode pad and striped line of the negative film used by preparation of Example 1 was formed by developing.

  Next, the plating exposed from the photosensitive film was removed with an etching solution, and then the remaining photosensitive film was peeled off. As a result, a copper foil pattern substantially corresponding to the negative film was formed.

  100 test patterns were produced in the same manner as in Example 1. Every time one test pattern was produced, it was necessary to repeat the operations from drilling to copper plating, patterning, etching, and peeling, and a great deal of time was spent on producing 100 test patterns.

  Next, after forming a hardened solder resist on the front and back of the substrate in the same manner as in Example 1, a tin plating with a thickness of 3 μm was formed on the surface of the electrode pad by electroless plating. Finally, the wiring board of Comparative Example 1 was obtained by cutting in the same manner as in Example 1.

[result]
(1) In Example 1, since a base material does not exist between the metal layers formed in a pattern, Example 1 can be thinned and has excellent thermal conductivity. Moreover, since the structure of Example 1 is a structure which covers both surfaces of a metal layer with the insulating layer which has a softness | flexibility, it became possible to use Example 1 as a flexible wiring board. On the other hand, since Comparative Example 1 has a base material (polyimide film) between the metal layer on the front surface and the metal layer on the back surface, there is a limit to reducing the thickness of Comparative Example 1, and the heat conduction of Comparative Example 1 is limited. It was difficult to improve sex. Further, since Comparative Example 1 has equipment, Comparative Example 1 could not be made as flexible as Example 1.
(2) In Example 1, drilling and plating for electrically connecting the front surface and the back surface of the wiring board were unnecessary. On the other hand, in Comparative Example 1, a drilling process and a plating process for electrically connecting the wiring circuit on the front surface and the wiring circuit on the back surface are necessary, and the manufacturing cost increases.
(3) In Example 1, since the patterned metal layer was formed on the wiring board by transfer, it was not necessary to form the metal layer pattern on the wiring board by the photolithographic method, and the manufacturing cost could be reduced. . For this reason, Example 1 can be manufactured by the roll-to-roll method, and productivity can be improved further. On the other hand, in Comparative Example 1, since it is necessary to form a metal layer pattern on the wiring board by photolithography every time one wiring board is manufactured, the manufacturing cost is increased. Further, Comparative Example 1 cannot be produced by the roll-to-roll method, and it is difficult to increase productivity.

DESCRIPTION OF SYMBOLS 1 Wiring board 10 Base material part 20,116,216 Metal layer 22 1st main surface 24 2nd main surface 26 Side surface 30 1st insulating layer 40 2nd insulating layer 42,52,114 Opening part 50 3rd Insulating layer 110 Conductive base material 112 Insulating layer 120, 220 Stripping base material 122 Adhesive layer 130 First uncured insulating layer 132 First cured insulating layer 140 Second uncured insulating layer 210 Rotating body 310 Plating Tank 312 Plating solution 320, 330, 350 Scroll 340 Press roll 352 Cover film 360 UV irradiation device

Claims (9)

A base material portion comprising a metal layer having a first main surface, a second main surface and side surfaces and formed in a pattern, and a first insulating layer disposed around the metal layer;
A wiring board comprising: a second insulating layer covering the first main surface of the metal layer; and a third insulating layer covering the second main surface of the metal layer.   The wiring board according to claim 1, wherein the side surface of the metal layer has a tapered shape from the first main surface toward the second main surface.   At least one of a part of the first main surface of the metal layer and a part of the second main surface of the metal layer is exposed from the second insulating layer or the third insulating layer. The wiring board according to claim 1 or 2.   At least one of the second insulating layer and the third insulating layer is made of a cured product of a thermosetting and / or active energy ray-curable solder resist. Wiring board as described in. Preparing a conductive substrate whose surface is covered with an insulating layer having an opening (A),
Forming a metal layer in the opening by plating (B),
A step (C) of having a pressure-sensitive adhesive layer on one surface and preparing a flexible peeling substrate;
Adhering the pressure-sensitive adhesive layer of the substrate for peeling to the metal layer and peeling the conductive substrate from the metal layer (D),
A step (E) of forming a first uncured insulating layer on the peeling substrate so that the metal layer is embedded;
Curing the first uncured insulating layer to form a first cured insulating layer (F),
A step (G) of peeling the peeling substrate from the metal layer and the first cured insulating layer;
A step (H) of forming a second uncured insulating layer on a release surface of the metal layer and the first cured insulating layer; and a second cured insulating layer by curing the second uncured insulating layer. A method for manufacturing a wiring board, comprising the step (I) of forming a substrate.   6. The wiring board according to claim 5, wherein in the step (B), a metal layer is formed in the opening so that a cross-sectional area in a planar direction of the conductive base material decreases as the distance from the insulating layer increases. Production method.   In the step (E) and the step (H), at least one of the first uncured insulating layer and the second uncured insulating layer is formed so that a part of the metal layer is exposed. Item 7. A method for manufacturing a wiring board according to Item 5 or 6.   In the step (F) and the step (I), the curing is performed by photolithography so that a part of the metal layer is exposed from at least one of the first cured insulating layer and the second cured insulating layer. The method for manufacturing a wiring board according to claim 5, wherein an insulating layer is formed.   9. At least one of the first uncured insulating layer and the second uncured insulating layer is made of a thermosetting and / or active energy ray curable solder resist. The manufacturing method of the wiring board as described in an item.