JP5251828B2 - Three-dimensional circuit board manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a three-dimensional circuit board, and more particularly, to a method for manufacturing a three-dimensional circuit board by transferring a metal wiring layer to an outer peripheral surface of a cylindrical body.

  As electronic devices such as mobile phones become smaller, more functional, and lower in cost, it is required to mount a circuit board in a compact manner on the inner and outer surfaces of cylindrical parts of the electronic device. As a circuit board for that purpose, there is a case where a three-dimensional circuit board is required instead of a planar one.

  Also in the field of copying machines, for example, as proposed in Japanese Patent Application Laid-Open No. 2003-084560 (Patent Document 1), the outer peripheral surface of a cylindrical body made of metal or resin is proposed. The use of a developer carrying member (developing roller) in which a wiring circuit is formed throughout has been studied.

  As a means for forming a circuit board on the outer peripheral surface of such a cylindrical body, a method of sticking a film-like circuit board provided with electrode wiring on the surface of an insulating film such as polyimide to the outer peripheral surface of the cylindrical body is conceivable. Since this method can manufacture a three-dimensional circuit board in a large amount and at low cost, it can be said that this method is simpler and easier than the method of directly forming electrode wiring on the outer peripheral surface of the cylindrical body.

  However, when the film-like circuit board is attached to the outer peripheral surface of the cylindrical body, there is a drawback that an overlap or a large gap tends to occur at both ends of the attached film-like circuit board. If there are overlaps or large gaps at both ends of the film-like circuit board, the wiring constituting the circuit may be short-circuited or poorly connected, and in the case of a copying machine, toner may enter the gap.

  Therefore, when the film-like circuit board is attached to the outer peripheral surface of the cylindrical body, it is necessary that both ends of the film-like circuit board do not overlap and that the gap between the ends is allowed to be small enough. Become. However, even when the film-like circuit board is cut accurately and pasted accurately, there is a variation in dimensions due to the cutting of the film-like circuit board, and the variation in the finished diameter remains in the cylindrical body itself. It has been extremely difficult to prevent the occurrence of overlapping and gaps exceeding the allowable range at both ends of the substrate.

  On the other hand, Japanese Patent Laid-Open No. 10-051108 (Patent Document 2) uses a transfer sheet in which a metal layer is bonded to the surface of a resin film via an adhesive layer, and then a wiring pattern is formed by etching. A technique for transferring metal wiring onto a typical insulating substrate is described. According to this method, the metal wiring can be transferred to an accurate position of the planar insulating substrate, but the formation of the three-dimensional circuit substrate by transfer to the outer peripheral surface of the cylindrical body is not described.

  In addition, when a metal layer is attached to the resin film surface via an adhesive layer, there is a problem that wrinkles are generated in the attached thin metal layer because tension cannot be applied when the thickness of the metal layer is 10 μm or less. there were. Also, if the resin film is peeled off when transferring the metal wiring to the insulating substrate, the adhesive layer is peeled off and transferred together with the metal wiring, and there is an adhesive layer (adhesive) at the contact part of the resulting circuit board, resulting in poor conduction It was easy to happen.

JP 2003-084560 A JP-A-10-051108

  In view of the above-described problems of the prior art, the present invention has a problem that overlaps and gaps are generated at both ends of a metal wiring layer when a metal wiring layer is formed on the outer peripheral surface of a cylindrical body to manufacture a three-dimensional circuit board. An object of the present invention is to provide a method for manufacturing a three-dimensional circuit board that can eliminate the occurrence of wrinkles and the like in a metal wiring layer and can prevent conduction failure due to adhesion of an adhesive or the like.

  In order to achieve the above object, a method for manufacturing a three-dimensional circuit board provided by the present invention is a film-like circuit in which a metal wiring layer is directly formed on an insulating film surface with respect to an insulating adhesive layer formed on an outer peripheral surface of a cylindrical body. The metal wiring layer on the surface of the insulating film is placed on the insulating adhesive layer on the outer peripheral surface of the cylindrical body by pressing the end of the wiring pattern on the substrate and rotating the cylindrical body along the surface of the film-like circuit board from this state. It is characterized by being transferred to.

  In the method for manufacturing a three-dimensional circuit board according to the present invention, the film-like circuit board is formed by directly forming a metal thin film on the surface of the insulating film by vapor deposition or sputtering, and forming a metal layer thereon by electroplating. After the formation, it is obtained by etching to form a metal wiring layer having a predetermined wiring pattern.

  According to the present invention, it is possible to eliminate the occurrence of overlapping and gaps at both ends of the film-like circuit board, which is inevitable by the conventional method of attaching the film-like circuit board to the outer peripheral surface of the cylindrical body. Furthermore, no wrinkles or the like occur in the metal wiring layer formed on the outer peripheral surface of the cylindrical body, and there is no conduction failure due to adhesion of an adhesive or the like, so that a high-precision and high-performance three-dimensional circuit board can be obtained. Can do.

It is drawing which shows the manufacturing method of the three-dimensional circuit board by this invention, (a) is the state which pressed the wiring pattern edge part of the film-form circuit board hold | maintained to the plate of the sticking apparatus on the insulating adhesive layer of the cylindrical body. FIG. 4B is a schematic cross-sectional view showing a state where the metal wiring layer is transferred to the insulating adhesive layer while rotating the cylindrical body along the surface of the film-like circuit board.

BRIEF DESCRIPTION OF THE DRAWINGS It is drawing for demonstrating a three-dimensional circuit board, (a) is general | schematic sectional drawing which shows the three-dimensional circuit board obtained by this invention, (b) is sticking the conventional film-like circuit board on a cylindrical body outer peripheral surface. It is a schematic sectional drawing which shows the three-dimensional circuit board obtained by the attaching method.

1 is a schematic plan view showing a film-like circuit board in which a metal wiring layer is directly formed on the surface of an insulating film used in Example 1. FIG.

FIG. 4 is a schematic plan view showing a three-dimensional circuit board obtained by transferring a metal wiring layer of the film-like circuit board of FIG. 3 to a cylindrical outer peripheral surface.

  In the method for manufacturing a three-dimensional circuit board according to the present invention, a film-like circuit board in which a metal wiring layer is directly formed on an insulating film surface without using an adhesive or the like is used, and the metal wiring layer of the film-like circuit board is formed. It transfers on the insulating adhesive layer formed in the cylindrical outer peripheral surface. Therefore, since the metal wiring layer is formed directly on the surface of the insulating film, the metal wiring layer does not wrinkle during the formation or transfer, and adhesion of an adhesive that causes poor conduction is also possible. In addition, by using transfer, it is possible to eliminate the occurrence of overlapping and gaps at both ends of the metal wiring layer.

  The film-like circuit board is manufactured by directly forming a metal thin film such as copper or nickel on the surface of the insulating film by vapor deposition or sputtering, and forming a metal layer having a predetermined thickness on the metal thin film by electroplating. Form. Thereafter, the metal layer and the underlying metal thin film are etched to form a metal wiring layer having a predetermined wiring pattern, whereby a film-like circuit board can be obtained.

  To explain in more detail by a preferred embodiment, first, a Cu thin film having a thickness of 0.01 to 1.0 μm is directly formed as a metal thin film on one side of an insulating film having a thickness of 25 μm or more by a sputtering method or a vacuum deposition method. To do. In addition, since the rigidity of the insulating film is insufficient if it is extremely thin, about 50 μm is convenient. Moreover, since the processing time is required for forming the Cu thin film to be thick, it is preferably about 0.05 to 0.1 μm.

  Next, Cu plating is performed by electroplating to form a Cu layer having a predetermined thickness, for example, about 1 to 10 μm, on the Cu thin film. A resist layer is formed on the Cu layer, and a resist mask is formed on the Cu layer by exposing and developing using a wiring pattern mask. Thereafter, an etching process is performed and the resist mask is peeled off, whereby a film-like circuit board having a Cu wiring layer on which a predetermined wiring pattern is formed by a Cu metal layer (= Cu thin film + Cu layer) can be obtained.

  On the other hand, as the cylindrical body for transferring the metal wiring layer from the film-like circuit board, a metal or a resin can be used depending on the application. Further, an insulating adhesive layer for adhering and holding the metal wiring layer is formed in advance on the outer peripheral surface of the cylindrical body. In forming the insulating adhesive layer, a liquid adhesive may be applied, but it is preferable to use a tape-like insulating double-sided adhesive in that a certain thickness can be easily obtained.

  Specifically, a tape-like insulating double-sided adhesive is cut to a length that matches the outer periphery of the cylindrical body and slightly wider than the wiring pattern of the film-like circuit board, and is wound around the outer peripheral surface of the cylindrical body Thus, an insulating adhesive layer can be formed. The tape-like insulating double-sided adhesive may be a type that exhibits adhesiveness at room temperature or a type that exhibits adhesiveness by heating. The insulating adhesive layer is preferably thicker than the metal wiring layer to be transferred.

  Next, a method for transferring the metal wiring layer of the film-like circuit board onto the insulating adhesive layer formed on the outer peripheral surface of the cylindrical body will be specifically described with reference to FIG. First, the film-like circuit board 10 in which the metal wiring layer 2 is directly formed on the surface of the insulating film 1 is held on the plate 11 of the sticking device. As a holding means to the plate 11, there are a method of adsorbing the back surface of the film-like circuit board 10, a method of adhering the back surface, and the like. On the other hand, the insulating adhesive layer 3 is formed on the outer peripheral surface of the cylindrical body 12 by attaching a tape-like insulating double-sided adhesive.

  As shown in FIG. 1A, the insulating adhesive layer 3 of the cylindrical body 12 is pressed against the end of the wiring pattern of the metal wiring layer of the film-like circuit board 10 held on the plate 11. Subsequently, as shown in FIG. 1B, the plate 11 is moved in the horizontal direction while rotating the cylindrical body 12, and the cylindrical body 12 is rotated once along the surface of the film-like circuit board 11. The layer 2 is peeled off from the insulating film 1 at the base metal thin film portion and transferred to the insulating adhesive layer 3 of the cylindrical body 12. In the above transfer step, the pressure when pressing the metal wiring layer 2 against the insulating adhesive layer 3 is preferably in the range of 0.1 to 1.0 MPa.

  As shown in FIG. 2A, the three-dimensional circuit board obtained by the above-described method of the present invention has a metal wiring layer 2 having a predetermined wiring pattern on the insulating adhesive layer 3 on the outer peripheral surface of the cylindrical body 12. It has an adhesively held structure. In particular, by adopting a method of transferring the metal wiring layer on the surface of the insulating film onto the insulating adhesive layer on the outer peripheral surface of the cylindrical body, the length between the both ends of the wiring pattern of the metal wiring layer is formed on the outer peripheral surface of the cylindrical body. By making it equal to the outer peripheral length of the layer, it is possible to easily eliminate the occurrence of overlap and gaps at both ends of the transferred wiring pattern.

  On the other hand, as described above and as shown in FIG. 2B, in the three-dimensional circuit board produced by the conventional method of attaching the film-like circuit board 10 to the outer peripheral surface of the cylindrical body 12, the film-like circuit board 10 Since there are variations in dimensions due to cutting and variations in the finished diameter of the cylindrical body 12, the frequency of occurrence of overlapping and large gaps 4 at both ends of the film-like circuit board 10 is extremely high.

  When the metal wiring layer is transferred from the insulating film to the insulating adhesive layer of the cylindrical body, the ease of peeling of the metal wiring layer from the insulating film, that is, the adhesion between the metal wiring layer and the insulating film is affected. The lower limit of the adhesiveness that can be transferred is the process up to the formation of the wiring pattern. For example, the metal layer (including the underlying metal thin film, the same applies hereinafter) is peeled off by the etchant shower or the resist mask is peeled off. That is, the layer does not peel off. Moreover, the upper limit of adhesiveness is a grade which only a metal wiring layer peels, without leaving a residue.

  Specifically, when the pitch of the wiring pattern of the metal wiring layer is in a general range of 50 to 500 μm, the adhesion between the insulating film and the metal wiring layer is 98 to 98 in terms of peel strength of the metal layer before patterning. A range of 321 N / m is preferred. The peel strength used for the evaluation of the adhesion of the metal wiring layer is determined when the metal layer is formed by etching to have a line width of 10 mm, the end is gripped and peeled off in a 90 ° direction with respect to the insulating film. It refers to the required force (unit N / m).

  In order to perform good transfer, it is desirable to control the adhesion between the insulating film and the metal wiring layer. As a method for controlling adhesion, for example, after forming a metal thin film or metal layer on an insulating film, heating is performed to reduce the adhesive force at the interface between the resin and the metal, or the insulating film before film formation There is a method in which a resin is applied to increase or decrease the adhesive strength. In addition, the metal layer formed on the insulating film by the vapor deposition method or the sputtering method and the electroplating method has preferable adhesion for transfer under general conditions.

  In addition, the insulating adhesive layer provided on the outer peripheral surface of the cylindrical body needs to have an adhesive force that allows the metal wiring layer having the above-described adhesion to be adhered and peeled from the insulating film. The tape-like double-sided adhesive that is generally used as an adhesive with insulation has such an adhesive force, and can be peeled off from the insulation film by bonding the metal wiring layer. it can.

[Example 1]
A 0.1 μm thick Cu thin film was formed by sputtering on the surface of a 50 μm thick polyethylene terephthalate (PET) film (Toray: T60), and then heated at 120 ° C. for 1 hour to control adhesion. . Next, a Cu layer having a thickness of 8 μm was formed on the Cu thin film by copper sulfate plating (manufactured by Sugawara Eugelite: Cube Light 21).

  About the obtained composite material, the adhesiveness of Cu metal layer (= Cu thin film + Cu layer) and PET film was evaluated. That is, this composite material is etched to form a line width of the Cu metal layer to 10 mm, and the end of the Cu metal layer is gripped and peeled off in a direction of 90 ° with respect to the PET film. The peel strength was measured and found to be 98 N / m.

  Next, a dry film resist (Asahi Kasei Co., Ltd .: AQ-1158) was attached on the Cu metal layer of the composite material, and exposure and development were performed using a predetermined mask to form a resist mask. Subsequently, after performing an etching process to form a wiring pattern, the remaining resist mask was peeled off to obtain a film-like circuit board having a Cu wiring layer of a comb-like wiring pattern shown in FIG.

  At this time, using the composite material having a peel strength of 98 N / m, three types of film-like circuit boards having different wiring pattern pitches of the Cu wiring layer were produced. That is, the pitch was 500 μm (line width 250 μm, interval 250 μm), pitch 100 μm (line width 50 μm, interval 50 μm), and pitch 50 μm (line width 25 μm, interval 25 μm).

  However, although it is unclear whether the Cu wiring layer with a pitch of 100 μm and a pitch of 50 μm is in the etching process or the resist mask is peeled off, a part of the Cu wiring layer is peeled off. Therefore, production and evaluation of a three-dimensional circuit board by transfer were advanced only for a film-like circuit board having a Cu wiring layer having a wiring pattern with a pitch of 500 μm without peeling.

  That is, an insulating adhesive layer was formed on the outer peripheral surface of an aluminum pipe (diameter 16 mm, length 300 mm) using a tape-like insulating double-sided adhesive (manufactured by Tessa Tape: thermosetting type 8405). The Cu wiring layer of the film-like circuit board was transferred to the insulating adhesive layer on the outer peripheral surface of the aluminum pipe using the sticking apparatus shown in FIG.

  Specifically, the aluminum pipe on which the adhesive layer is formed is heated to 90 ° C. with an infrared heater, and the end of the wiring pattern of the Cu wiring layer of the film-like circuit board in which the PET film side is sucked and fixed to the plate of the sticking device is set to 0. The pressure was applied at a pressure of 2 MPa. Subsequently, the Cu wiring layer was peeled off from the PET film and transferred to the insulating adhesive layer of the aluminum pipe by rotating the cylindrical body once along the surface of the film-like circuit board.

  After the aluminum pipe returned to room temperature, the Cu wiring layer transferred onto the insulating adhesive layer of the aluminum pipe was observed, and no overlap or gap was generated at both ends of the Cu wiring layer. Moreover, it was confirmed by the external appearance confirmation by microscopic inspection (20 times) that there was no wrinkle or disconnection in the wiring pattern, and that the entire Cu wiring layer could be completely transferred. Furthermore, adhesion of an adhesive or the like was not observed on the Cu wiring layer on the outer peripheral surface of the cylindrical body, and good conductivity was obtained.

[Example 2]
A Cu thin film having a thickness of 0.1 μm was formed on the surface of a PET film having a thickness of 50 μm as in Example 1 (Toray: T60) by vacuum deposition. Next, as in Example 1, a Cu layer having a thickness of 8 μm was formed on the Cu thin film by copper sulfate plating. About the obtained composite material, when the adhesiveness of Cu metal layer and PET film was evaluated similarly to the said Example 1, the peel strength was 211 N / m.

  The Cu metal layer of this composite material was patterned in the same manner as in Example 1 to produce three types of film-like circuit boards with different pitches of wiring patterns of 500 μm, 100 μm, and 50 μm. However, a part of the Cu wiring layer with a pitch of 50 μm was peeled off. Thus, for a film-like circuit board having a Cu wiring layer with wiring patterns having a peeling pitch of 500 μm and 100 μm, a three-dimensional circuit board was manufactured and evaluated by transfer in the same manner as in Example 1 above.

  When the Cu wiring layer transferred onto the insulating adhesive layer of the aluminum pipe was observed, no overlap or gap was generated at both ends of the Cu wiring layer in both types of pitches of 500 μm and 100 μm. Moreover, it was confirmed by the external appearance confirmation by microscopic inspection (20 times) that there was no wrinkle or disconnection in the wiring pattern, and that the entire Cu wiring layer could be completely transferred. Furthermore, adhesion of an adhesive or the like was not recognized on the Cu wiring layer on the outer peripheral surface of the cylindrical body, and good electrical conductivity was obtained.

[Example 3]
In order to control adhesion, a resin (Jujo Chemical: GA4100) was applied to the surface of a PET film (Toray: T60) having the same thickness of 50 μm as in Example 1 and dried. A 0.1 μm Cu thin film was formed. Next, as in Example 1, a Cu layer having a thickness of 8 μm was formed on the Cu thin film by copper sulfate plating. About the obtained composite material, when the adhesiveness of Cu metal layer and PET film was evaluated similarly to the said Example 1, the peel strength was 321 N / m.

  The Cu metal layer of this composite material was patterned in the same manner as in Example 1 to produce three types of film-like circuit boards with different pitches of wiring patterns of 500 μm, 100 μm, and 50 μm. As a result, the Cu wiring layer did not peel off at all three pitches. Thus, three types of film-like circuit boards having Cu wiring layers of respective wiring patterns were manufactured and evaluated by transfer in the same manner as in Example 1 above.

  When the Cu wiring layer transferred onto the insulating adhesive layer of the aluminum pipe was observed, there was no overlap or generation of gaps at both ends of the Cu wiring layer in the three types of pitches of 500 μm, 200 μm and 100 μm. Moreover, it was confirmed by the external appearance confirmation by microscopic inspection (20 times) that there was no wrinkle or disconnection in the wiring pattern, and that the entire Cu wiring layer could be completely transferred. Furthermore, adhesion of an adhesive or the like was not observed on the Cu wiring layer on the outer peripheral surface of the cylindrical body, and good conductivity was obtained.

DESCRIPTION OF SYMBOLS 1 Insulating film 2 Metal layer 3 Insulating adhesive layer 4 Gap 10 Film-like circuit board 11 Plate 12 Cylindrical body

Claims (4)

After forming the metal wiring layer directly on the surface of the insulating film, this film-like circuit board is used by controlling the adhesion between the insulating film and the metal wiring layer by heating and reducing the adhesive strength at the interface. By pressing the end of the circuit board wiring pattern against the insulating adhesive layer formed on the outer peripheral surface of the cylindrical body, and rotating the cylindrical body along the surface of the film-like circuit board from this state, the surface of the insulating film A method of manufacturing a three-dimensional circuit board, comprising transferring the metal wiring layer onto an insulating adhesive layer on an outer peripheral surface of a cylindrical body.   The film-like circuit board is formed by directly forming a metal thin film on the surface of the insulating film by vapor deposition or sputtering, forming a metal layer thereon by electroplating, and then etching to form a metal wiring layer having a predetermined wiring pattern. The method for manufacturing a three-dimensional circuit board according to claim 1, wherein the three-dimensional circuit board is obtained by forming the step.   In the film-like circuit board, when the pitch of the wiring pattern of the metal wiring layer is 50 to 500 μm, the peel strength of the metal layer before patterning to the metal wiring layer is 98 to 321 N / m. The manufacturing method of the three-dimensional circuit board of Claim 1 or 2.   The length between both ends of the wiring pattern of the metal wiring layer directly formed on the surface of the insulating film is equal to the outer peripheral length of the insulating adhesive layer formed on the outer peripheral surface of the cylindrical body. The manufacturing method of the three-dimensional circuit board in any one of 1-3.

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