JP2010280105A - Method for forming image on surface of metal foil - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for directly forming an image or a pattern, achieving a sufficient contrast on the surface of a metal foil, onto the surface of the metal foil. <P>SOLUTION: Dots 5 are formed in a desired region on the surface of a metal foil 3, having a prescribed reflectance, on a base material 2. The dot parts or their peripheries are etched so as to form the non-through unevenness in which the dot parts are made convex or concave. By the unevenness, an image 8 having a low reflecting part 6 with a reflectance lower than the prescribed reflectance is formed in the desired region so as to obtain an image-formed product 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an image forming method on a metal foil surface, and more particularly to a method of forming a desired contrast on an electric wiring pattern, for example.

  For example, in an electrical wiring pattern made of copper foil, it may be required to form characters, numbers, barcodes, etc., which are product information, on the pattern. In this case, for example, as shown in FIG. 9, an image forming product is formed by forming a through portion 4 on the metal foil 3 on the base material 2 by etching or the like and making the through portion 4 an outline of a number 8 d. Obtaining 1d is performed.

  However, since the metal foil has a strong surface gloss, there is a problem that the contrast is insufficient and the visibility is poor only by the contour formation by the through portion 4. Also, the electrical wiring pattern is often formed on a transparent base material such as a resin film, and the base material or a member under the base material can be seen through from the penetrating portion, thereby further reducing the contrast. There is also.

  In addition, as another requirement, there is a case where strong gloss of the metal foil is disliked from the viewpoint of designability, and there is also a requirement to reduce the gloss only at a necessary portion.

  On the other hand, there is an attempt to form an image by forming a halftone dot on a metal surface by a printing technique without directly forming an image on the metal surface by a normal printing method or the like. For example, the following Patent Document 1 discloses a technique for forming a halftone dot mask using a photoresist and forming a permanent image having a gradation on the metal surface by half-etching the halftone dot on the surface of the metal material. It is disclosed.

JP 2001-225595 A

  However, Patent Document 1 merely discloses an image forming technique on a metal surface using halftone dots, and does not disclose application to a metal foil disposed on a substrate like an electric wiring pattern. .

  The present invention has been made in view of the above situation, and an object of the present invention is to provide a method for directly forming an image or pattern on the surface of the metal foil, which can provide sufficient contrast on the surface of the metal foil.

  As a result of intensive studies to solve the above problems, the present inventors have formed a predetermined halftone dot on the surface of the metal foil that has a low reflectance compared to the surface of the metal foil before processing. The halftone dot forming portion can be made into an image or a pattern, and it has been found that the above problems can be solved, and the present invention has been completed.

  According to the present invention, (1) a halftone dot is formed in a desired region on the surface of the metal foil having a predetermined reflectivity, and the halftone dot portion and / or the periphery thereof are etched to make the halftone dot portion a convex portion or An image forming method on the surface of a metal foil, wherein a non-penetrating unevenness as a recess is formed, and an image portion having a reflectance lower than the predetermined reflectance is formed in the desired region by the unevenness. . Etching a halftone dot portion means forming a concave portion in the halftone dot portion and leaving the periphery of the halftone dot as a convex portion, and the first to fourth embodiments to be described later are examples. Etching the periphery of a halftone dot means that the periphery of the halftone dot is etched to form a concave portion so that the halftone dot portion becomes a convex portion, and the halftone dot portion is left as a convex portion. The fifth embodiment is an example. Etching the halftone dot portion and the periphery thereof is an example of the sixth embodiment. Etching is performed around the halftone dot so that the halftone dot portion becomes a convex portion, thereby forming a concave portion. It means that the remaining convex part is also etched, preferably the top part of the convex part is etched on the curved surface, and the entire area is etched without the original metal foil surface in the image part. .

  Moreover, this invention is (2) The image formation method to the metal foil surface of (1) description which forms the said image part by etching the circumference | surroundings of the said dot part and making the said dot part a convex part.

  The present invention is also (3) the image forming method on the surface of the metal foil according to (2), wherein the top of the convex portion is curved.

  Moreover, this invention is (4) The image formation method to the metal foil surface in any one of (1) to (3) whose said image part is a predetermined surface pattern.

  Moreover, this invention is (5) The image formation method to the metal foil surface in any one of (1) to (3) whose said image part is a product information code.

  The present invention also includes (6) a mask forming step of forming a mask having a dot-like through portion on the surface of the metal foil using a resist, and the metal on the surface of the metal foil using the mask. (1) to (5) comprising: a half-etching step that forms a halftone dot that is a recess that does not penetrate through the foil by etching; and a mask removal step that removes the mask from the surface of the metal foil that has undergone the half-etching step. An image forming method on a metal foil surface according to any one of the above.

  In the mask forming step, the present invention may further include forming a mask having a penetrating portion for patterning the metal foil itself in addition to the dot-like penetrating portion. The method for forming an image on the surface of the metal foil according to (6), wherein the patterning of the metal foil and the formation of the image portion are simultaneously performed by simultaneously patterning the metal foil itself.

  Moreover, this invention was formed in the half etching process by the blackening agent which blackens the surface of the metal which comprises the said metal foil further between the said half etching process and the said mask removal process. The image forming method on the surface of the metal foil according to (6) or (7), comprising a blackening step of blackening the inside of the halftone dots.

  According to the present invention, a desired image or pattern can be formed at an arbitrary position on the surface of a metal foil such as an electric wiring pattern.

(A) is a top view which shows an example of the image formation product produced by the 1st embodiment of the image formation method to the metal foil surface of this invention. (B) is an expanded sectional view which shows an example of the image forming product produced by the 1st embodiment of the image forming method to the metal foil surface of this invention. It is an enlarged plan view which shows a low reflection part. (A)-(e) is a schematic diagram which shows sequentially a mode that a low reflection part is formed by the 1st embodiment of the image formation method to the metal foil surface of this invention. (A) is a top view which shows an example of the image formation product produced by the 3rd embodiment of the image formation method to the metal foil surface of this invention. (B) is an expanded sectional view which shows an example of the image formation product produced by the 3rd embodiment of the image formation method to the metal foil surface of this invention. (A)-(f) is a schematic diagram which shows sequentially a mode that a low reflection part is formed by the 3rd embodiment of the image formation method to the metal foil surface of this invention. (A) is a top view which shows an example of the image formation product produced by the 5th embodiment of the image formation method to the metal foil surface of this invention. (B) is an enlarged sectional view showing an example of an image forming product produced by the fifth embodiment of the image forming method on the metal foil surface of the present invention. (A)-(e) is a schematic diagram which shows sequentially a mode that a low reflection part is formed by the 5th embodiment of the image formation method to the metal foil surface of this invention. (A) is a top view which shows an example of the image formation product produced by the 6th embodiment of the image formation method to the metal foil surface of this invention. (B) is an expanded sectional view which shows an example of the image formation product produced by the 6th embodiment of the image formation method to the metal foil surface of this invention. (A) is a top view which shows an example of the image forming product produced by the conventional method. (B) is an expanded sectional view which shows an example of the image forming product produced by the conventional method.

<First Embodiment>
First, an image forming product 1 produced by the first embodiment of the image forming method on the metal foil surface of the present invention will be briefly described with reference to the drawings. Fig.1 (a) is a top view which shows an example of the image formation product produced by the 1st embodiment of the image formation method to the metal foil surface of this invention. FIG.1 (b) is an expanded sectional view which shows an example of the image formation product produced by the 1st embodiment of the image formation method to the metal foil surface of this invention.

  In the image forming product 1, the patterned metal foil 3 is formed on the surface of the substrate 2, and the image 8 is formed on the surface of the metal foil 3. The image 8 is formed by an outer peripheral through portion 4 provided through the metal foil 3 on the outer periphery of the image 8 and a halftone dot 5 that is a concave portion that does not penetrate the metal foil 3 gathered inside the outer peripheral through portion 4. And a low reflection portion 6.

  Next, the low reflection portion 6 will be described with reference to FIG. FIG. 2 is an enlarged plan view showing the low reflection portion 6. The low reflection part 6 is formed by gathering the halftone dots 5, and the reflectance is lower than that around the low reflection part 6 due to the light scattering action. The halftone dots 5 are substantially circular concave portions having a diameter d in plan view, and are arranged with a predetermined interval p. In this embodiment, all the halftone dots 5 are arranged in a staggered pattern in plan view so that the distance between the centers of the halftone dots 5 is the same as p, but the present invention is not limited to this and can be designed as appropriate. The depth of the halftone dot 5 is not particularly limited as long as it is shallower than the thickness of the metal foil 3. The diameter d of the halftone dot 5 is preferably 30 to 80 μm, and more preferably 40 to 60 μm. Further, the interval p at which the halftone dots 5 are provided is preferably 40 to 100 μm, and more preferably 60 to 80 μm.

  The image 8 formed on the image forming product 1 has an outer peripheral edge defined by the outer peripheral penetration part 4, and the inner part partitioned by the outer peripheral penetration part 4 has a reflectance higher than that of the outer part due to the presence of the low reflection part 6. The contrast is improved. That is, an image portion having a reflectance lower than the predetermined reflectance is formed by a non-penetrating halftone dot 5 in a desired region on the surface of the metal foil 3 having a predetermined reflectance. Contrast is improved. For this reason, the image 8 is on the surface of the metal foil 3 having a predetermined reflectance, and is easy to visually recognize or identify with an automatic identification device. “Predetermined reflectance” means the reflectance of the surface of the metal foil 3 itself.

  Examples of such an image forming product 1 include a wiring pattern of an electric circuit provided on the surface of the substrate 2. Since the wiring pattern of such an electric circuit is formed of the metal foil 3 on the surface of the substrate 2, the above-described image 8 is formed on the wiring pattern (metal foil 3), whereby the wiring pattern It becomes possible to embed a product information code in the product, which facilitates product management.

  As a comparison with the image forming product 1, a conventional image forming product 1d will be described with reference to FIG. FIG. 9A is a plan view showing an example of an image forming product produced by a conventional method. FIG. 9B is an enlarged cross-sectional view illustrating an example of an image forming product manufactured by a conventional method.

  As shown in FIG. 9, in the conventional image forming product 1d, the image 8d is formed only by the outer peripheral through portion 4 provided on the outer peripheral edge of the image 8d. For this reason, the reflectance of the inside and the outside partitioned by the outer peripheral through portion 4 is the same, and there is no contrast. For this reason, the image 8d is difficult to visually recognize or identify with an automatic identification device.

  Next, in the image forming method on the surface of the metal foil of this embodiment, a procedure for forming the low reflection portion 6 that is a set of halftone dots 5 will be described with reference to FIG. FIGS. 3A to 3E are schematic views sequentially showing how the low reflection portion 6 is formed by the first embodiment of the image forming method on the surface of the metal foil of the present invention.

  The image 8 by the image forming method on the surface of the metal foil of the present embodiment is formed on the metal foil 3 laminated on the surface of the substrate 2 as shown in FIG. First, the base material 2 and the metal foil 3 used in the image forming method on the surface of the metal foil of this embodiment will be described.

  Examples of the substrate 2 include polyethylene resins, polypropylene resins, cyclic polyolefin resins, polystyrene resins, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, polyvinyl chloride resins, and fluorine resins. , Poly (meth) acrylic resins, polycarbonate resins, polyethylene terephthalate (PET), polyester resins such as polyethylene naphthalate, various polyamide resins such as nylon, polyimide resins, polyamideimide resins, polyaryl phthalate resins Various resin sheets such as resin, silicone resin, polysulfone resin, polyphenylene sulfide resin, polyethersulfone resin, polyurethane resin, acetal resin, cellulose resin, paper, glass, glass Substrates such as for electric wirings such Suepokishi the like, but if the base material 2 capable of laminating a metal foil 3 on the surface is not particularly limited.

  The metal foil 3 is laminated on the base material 2 by a known means. The metal constituting the metal foil 3 is not particularly limited as long as it can be corroded by an etching solution, such as iron alloy, copper, and aluminum. The thickness of the metal foil 3 may be appropriately determined according to the use of the image forming product 1. For example, if the image forming product 1 is an electric wiring board, about 10 to 50 μm is preferable.

  The image forming method on the surface of the metal foil of this embodiment includes a mask forming step, a half etching step, and a mask removing step. Next, each of these steps will be described.

[Mask formation process]
First, the mask forming process will be described. This step is a step of forming a mask having a dot-like through portion on the surface of the metal foil 3 using a resist.

  In the mask formation step, as shown in FIG. 3B, first, a resist film 7 is formed on the surface of the metal foil 3. The resist used to form the resist film 7 may be a negative type that cures when irradiated with active energy rays such as ultraviolet rays and electron beams, or softens when irradiated with active energy rays. Alternatively, a positive type that can be dissolved and removed may be used. As such a resist, a known resist can be used without particular limitation.

  The resist film 7 is exposed to light using a photomask on which a graphic pattern of halftone dots 5 is formed, and then developed, so that the resist film 7 has substantially the same dimensions as the photomask as shown in FIG. The resist is patterned. On the photomask used for patterning, the already-described figure pattern of the substantially circular halftone dot 5 is formed with a desired diameter d and a desired interval p. In the patterned resist film 7 (hereinafter also referred to as “mask 7”), penetrating portions 71 corresponding to the locations where the halftone dots 5 are formed are formed. The resist film 7 in which the penetrating portion 71 is formed serves as a mask 7 when the metal foil 3 is etched.

[Half etching process]
Next, the half etching process will be described. This step is a step of forming a halftone dot 5 which is a recess not penetrating the metal foil 3 on the surface of the metal foil 3 by etching using the mask 7 formed in the mask forming step described above.

  The half etching process is performed by bringing the etching solution into contact with the metal foil 3. At this time, if the resist film 7 serving as a mask exists on the surface of the metal foil 3, the etching solution cannot come into contact with the metal foil 3, so that the metal foil 3 remains as it is in the portion where the mask 7 exists. On the other hand, in the portion where the mask 7 does not exist, the metal foil 3 comes into contact with the etching solution and corrodes, and a recess is formed on the surface of the metal foil 3.

  As an etching solution used in the half-etching process, a known etching solution can be used without particular limitation as long as it can corrode the metal foil 3. When the metal foil 3 is etched, halftone dots 5 are formed on the surface of the metal foil 3 as shown in FIG.

  As already described, the halftone dot 5 is formed as a recess that does not penetrate the metal foil 3, that is, a recess whose depth is smaller than the thickness of the metal foil 3. In order to form such a halftone dot 5, the diameter of the penetrating portion 71 provided in the resist film 7 and the time for etching the metal foil 3 are appropriately adjusted. For example, the depth of the halftone dot 5 decreases as the diameter of the penetrating portion 71 decreases, and the depth of the halftone dot 5 increases as the diameter of the penetrating portion 71 increases. Further, as the time for etching the metal foil 3 becomes shorter, the depth of the halftone dot 5 becomes smaller, and as the time for etching the metal foil 3 becomes longer, the depth of the halftone dot 5 becomes larger. For example, if a copper foil with a thickness of 10 to 50 μm is etched for 1 to 3 minutes using an aqueous solution of ferric chloride with a specific gravity of 1.3 to 1.6 (liquid temperature 50 ° C.) as an etching solution, In order to form a non-penetrating halftone dot 5, it is preferable to form a substantially circular penetrating portion 71 having a diameter of 40 to 60 μm in the mask. When the diameter of the penetrating portion 71 is 40 μm or more, a halftone dot 5 that is a recess can be formed on the surface of the copper foil, and when the diameter of the penetrating portion 71 is 60 μm or less, the dot 5 is not penetrating Can be. In the above case, the diameter of the halftone dots 5 formed on the metal foil 3 is 60 to 100 μm. That is, in this case, overetching occurs, and the outer diameter of the recessed portion of the halftone dot 5 to be etched is larger than the diameter of the through-hole portion 71 of the mask. As described above, the relationship between the mask diameter and the dot diameter can be appropriately designed depending on the etching conditions.

  In the half-etching process, the outer peripheral through portion 4 penetrating the metal foil 3 is also formed at the same time. In order to form the outer peripheral through portion 4 in the half-etching step, the mask 7 has a larger diameter (width) than the through portion 71 for forming the halftone dot 5 and a through portion for manufacturing the outer peripheral through portion (see FIG. (Not shown). As described above, the larger the diameter (width) of the penetrating portion provided in the mask is, the deeper the concave portion formed in the metal foil 3 is, so that the penetrating portion for forming the outer peripheral penetrating portion (not shown) is made of metal. By setting the diameter (width) sufficient to allow the foil 3 to penetrate, the outer peripheral penetration portion 4 can be provided at the same time as the halftone dot 5 is provided.

  In addition, in the mask formation process described above, in addition to the dot-shaped through portion 71, a mask 7 having a through portion (not shown) for patterning the metal foil 3 itself is manufactured, and half-etching is performed. In the process, the metal foil 3 itself can be patterned at the same time. Taking the wiring of the electric circuit as an example, if the pattern (penetrating portion 71) for forming the halftone dots 5 already described is provided on the mask 7 together with the pattern for forming the wiring of the electric circuit on the copper foil surface 3 Good. In this case, a desired image 8 can be formed on the wiring of the electric circuit.

[Mask removal process]
Next, the mask removal process will be described. This step is a step of removing the mask 7 from the surface of the metal foil 3 that has undergone the half-etching step.

  In order to remove the mask 7 (resist film) from the surface of the metal foil 3, a known stripping solution for stripping the resist film may be used. Since there are various known stripping solutions, a stripping solution capable of stripping the mask 7 may be appropriately selected according to the type of resist film used as the mask 7.

  In order to peel the mask 7 using the stripping solution, the stripping solution may be exposed to the mask 7. As such an exposure method, an immersion method, a spray method, or the like may be appropriately selected and used.

  When the mask 7 is removed from the surface of the metal foil 3, halftone dots 5 remain on the surface of the metal foil 3, as shown in FIG. By passing through the above process, the low reflection part 6 is formed.

According to the image forming method on the surface of the metal foil of this embodiment, the following effects are exhibited.
The image forming method on the surface of the metal foil according to the present embodiment has a low reflectance lower than the predetermined reflectance by a non-penetrating halftone dot 5 in a desired region on the surface of the metal foil 3 having a predetermined reflectance. The reflection part 6 (image part) is formed. For this reason, the reflectance of the image portion provided on the surface of the metal foil 3 is lower than the reflectance of the non-image portion, and the contrast between the image portion and the non-image portion is improved. Becomes easier. An example of such an image is a product information code.

  In addition, the image forming method on the surface of the metal foil of the present embodiment includes a mask forming step of forming a mask 7 having a dot-like through portion 71 on the surface of the metal foil 3 using a resist, A half-etching process in which a halftone dot 5 which is a recess that does not penetrate the metal foil 3 is formed on the surface of the metal foil 3 by etching, and a mask removal that removes the mask 7 from the surface of the metal foil 3 that has undergone the half-etching process. A process. Therefore, the image 8 including the low reflection portion 6 can be formed at low cost. Further, by adjusting the diameter (width) of the penetrating portion 71 formed in the mask 7, the depth of the recessed portion to be formed can be freely adjusted. By utilizing such characteristics, in the half-etching process, a halftone dot 5 that does not penetrate the metal foil 3 is formed to form an image portion including the low reflection portion 6, and at the same time, an outer periphery that penetrates the metal foil 3. The through portion 4 can be formed, or the metal foil 3 itself can be patterned. For this reason, an image part including the low reflection part 6 can be formed by an etching operation at a cost equivalent to the conventional method of patterning the metal foil 3. By adopting such an image forming method, for example, it becomes possible to incorporate image information such as a product information code inside the electric wiring pattern, and it becomes possible to easily manage the product.

<Second Embodiment>
Next, the image forming product 1 produced by the second embodiment of the image forming method on the surface of the metal foil of the present invention will be described. In the description of the second embodiment, the description of the parts overlapping with those of the first embodiment will be omitted, and the description will focus on the different parts.

  In the image forming method on the surface of the metal foil according to this embodiment, the image portion includes the low reflection portion 6 and the image portion is formed as a predetermined surface pattern. By forming such a surface pattern as an image portion, the reflectance of the surface of the metal foil 3 is lower than the reflectance of the surface of the original metal foil 3, and a design effect is imparted to the metal foil 3. Can do. For example, in the case where the metal foil 3 is used as an electric wiring, the present embodiment is formed on the surface of the electric wiring (metal foil 3) if the electric wiring (metal foil 3) is too conspicuous due to light reflection. The image may be formed. Thereby, the reflectance of the light of the electrical wiring (metal foil 3) falls, and the electrical wiring (metal foil 3) can be made not conspicuous.

  Here, the surface pattern means an image pattern provided on the surface of the metal foil 3 with a certain range. Specifically, as such an image pattern, a low reflection which is a set of halftone dots 5 already described. Part 6 is included. The surface pattern may be provided on the entire surface of the metal foil 3 or may be provided on a part of the metal foil 3.

According to the image forming method on the surface of the metal foil of this embodiment, the following effects are exhibited.
According to the image forming method on the surface of the metal foil of this embodiment, the image portion is formed as a predetermined surface pattern. This image portion is formed by the non-penetrating halftone dots 5 and has a lower reflectance than the non-image portion. Therefore, the reflectance of a part or all of the surface of the metal foil 3 can be reduced, and a design effect can be imparted. For example, by providing such an image (surface pattern) on the electrical wiring made of the metal foil 3, it becomes possible to reduce the reflectance of the electrical wiring and make it less noticeable.

<Third embodiment>
Next, an image forming product 1a produced by the third embodiment of the image forming method on the metal foil surface of the present invention will be described with reference to FIG. Fig.4 (a) is a top view which shows an example of the image formation product produced by the 3rd embodiment of the image formation method to the metal foil surface of this invention. FIG. 4B is an enlarged cross-sectional view showing an example of an image forming product manufactured by the third embodiment of the image forming method on the surface of the metal foil of the present invention. In the description of the third embodiment, the description of the parts overlapping with the first embodiment and the second embodiment will be omitted, and different parts will be mainly described.

  The image 8a formed by the image forming method on the metal foil surface of the third embodiment is different from the first embodiment in that the metal foil 3 is blackened on the inner surfaces of the halftone dots 5 and the outer peripheral penetration portion 4. There is a blackened portion 31 formed by. Since the image 8a of this embodiment is formed by the halftone dots 5 having the blackened portion 31 on the inner surface and the outer peripheral through portion 4, the contrast with respect to the non-image portion is further increased as compared with the image 8 formed in the first embodiment. To do.

  Here, when the blackening treatment is performed on the entire surface of the metal foil 3, a blackened portion that is an oxide film is formed on the entire surface of the metal foil 3, and therefore, particularly when the metal foil 3 is used as an electrical wiring, This causes a problem that soldering becomes impossible. In this respect, the image 8a formed in this embodiment is blackened only on the inner surface of the halftone dot 5 and the outer peripheral through portion 4 as shown in FIG. There are places that are not blackened. For this reason, even if it is a case where the metal foil 3 is used as an electrical wiring, soldering becomes possible.

  Next, in the image forming method on the surface of the metal foil of this embodiment, a procedure for forming the low reflection portion 6 that is a set of halftone dots 5 will be described with reference to FIG. FIGS. 5A to 5F are schematic views sequentially showing how the low reflection portion 6a is formed by the third embodiment of the image forming method on the surface of the metal foil of the present invention.

  As shown in FIGS. 5A to 5D, the image forming method on the surface of the metal foil of the present embodiment uses a resist to form a halftone dot on the surface of the metal foil 3 as in the first embodiment. A mask forming process having the mask 7 having the through-holes 71 and a half-etching process in which the mask 7 is used to form a halftone dot 5 which is a recess not penetrating the metal foil 3 on the surface of the metal foil 3 by etching. Prepare. Since the mask formation step and the half etching step are the same as described in the first embodiment, description thereof is omitted here.

  The image forming method on the surface of the metal foil of this embodiment is a blackening process shown in FIG. 5 (e) between the half etching process shown in FIG. 5 (d) and the mask removing process shown in FIG. 5 (f). A process is provided. Hereinafter, the blackening process will be described.

[Blackening process]
The blackening step was formed in the half etching step with a blackening agent that blackens the surface of the metal constituting the metal foil 3 with the mask 7 present on the surface of the metal foil 3 after the half etching step. In this step, the inside of the halftone dot 5 is blackened. As shown in FIG. 5 (d), at the stage where the half etching process is completed, the mask 7 is present on the surface of the metal foil 3, so that only the inner surface of the halftone dot 5 is exposed in the metal foil 3. It becomes. In this state, by exposing the surface of the metal foil 3 and the mask 7 to the blackening agent, the inner surface of the halftone dot 5 is blackened as shown in FIG. Of the surface of the metal foil 3, the portion covered with the mask 7 is not exposed to the blackening agent and thus is not blackened. By gathering the darkened halftone dots 5, the low reflection portion 6a is formed as in the first embodiment.

  The blackening agent used in the blackening step is not particularly limited as long as it can blacken the surface of the metal constituting the metal foil 3. Examples of such a blackening agent include an alkaline blackening solution and nickel plating. Among these, blackening with an alkaline blackening solution is preferably used.

  Here, “blackening” the surface of the metal is not limited to the meaning of making the surface of the metal black. It means that a light can be absorbed more than the metal surface. For this reason, “blackening” the surface of the metal is a concept including making the surface of the metal dark brown or brown.

  In this embodiment, as in the first embodiment, the outer peripheral through portion 4 that penetrates the metal foil 3 is also formed at the same time in the half etching step. The outer peripheral through-hole 4 formed in the half etching process is blackened on the inner surface in the blackening process.

  In the present embodiment, as in the first embodiment, in the mask forming step, in addition to the dot-shaped through portions 71, a through portion (not shown) for patterning the metal foil 3 itself is further provided. It is also possible to produce a mask having the metal foil 3 and pattern the metal foil 3 itself in the half-etching process. Thereby, similarly to the first embodiment, a desired image can be formed on the wiring of the electric circuit. However, in this embodiment, the blackened portion 31 is formed on the inner surface of the halftone dot 5. The image formed in this embodiment has a higher contrast than the image formed in the first embodiment.

  After the blackening process, through a mask removing process, as shown in FIG. 5 (f), halftone dots 5 having blackened portions 31 formed on the inner surface are formed on the surface of the metal foil 3. Since the mask removal step has already been described in the first embodiment, description thereof is omitted here.

According to the image forming method on the surface of the metal foil of this embodiment, the following effects are exhibited.
The image forming method on the surface of the metal foil of this embodiment is formed in the half etching step by a blackening agent that blackens the surface of the metal constituting the metal foil 3 between the half etching step and the mask removing step. A blackening step of blackening the inside of the halftone dots 5. Therefore, the contrast of the image portion formed on the surface of the metal foil 3 with respect to the non-image portion can be further increased. Moreover, since the blackening process is not performed on the surface of the metal foil 3 where the halftone dots 5 are not present, particularly when the image forming product 1a is used as an electrical wiring, good solderability can be obtained. it can.

<Fourth embodiment>
Next, an image forming product 1a produced by the fourth embodiment of the image forming method on the metal foil surface of the present invention will be described. In the description of the fourth embodiment, the description of the parts overlapping with the first to third embodiments will be omitted, and the description will focus on the different parts.

  In the image forming method on the surface of the metal foil of this embodiment, the image portion is composed of the low reflection portion 6a, and the image portion is formed as a predetermined surface pattern. Here, the black dots 31 are formed on the inner surface of the halftone dots constituting the low reflection portion 6a, as in the third embodiment. By forming such a surface pattern as an image portion, the reflectance of the surface of the metal foil 3 is lower than the reflectance of the surface of the original metal foil 3, and due to the presence of the blackened portion 31, Since the contrast is remarkably increased with respect to the original metal foil 3, a great design effect can be imparted to the metal foil 3. For example, in the case where the metal foil 3 is used as an electric wiring, the present embodiment is formed on the surface of the electric wiring (metal foil 3) if the electric wiring (metal foil 3) is too conspicuous due to light reflection. The image may be formed. Thereby, the light reflectance of the electrical wiring (metal foil 3) is lowered, and the electrical wiring (metal foil 3) can be made inconspicuous.

  Since the description of the surface pattern is as described in the second embodiment, the description thereof is omitted here.

According to the image forming method on the surface of the metal foil of this embodiment, the following effects are exhibited.
According to the image forming method on the metal foil surface of the present embodiment, the image portion is formed as a predetermined surface pattern. This image portion is formed by the non-penetrating halftone dots 5 and has a lower reflectance than the non-image portion. Further, since the blackened portion 31 is formed on the inner surface of the halftone dot 5, the contrast of this image portion is remarkably increased with respect to the non-image portion. Therefore, the reflectance of a part or all of the surface of the metal foil 3 can be reduced, and a design effect can be imparted. For example, by providing such a surface pattern on the electrical wiring made of the metal foil 3, the electrical wiring has a darkened appearance, the reflectance is significantly lowered and is not noticeable, while the blackened portion 31 is not visible. Since it is provided on the inner surface of the point 5, good solderability is maintained.

<Fifth embodiment>
Next, an image forming product 1b produced by the fifth embodiment of the image forming method on the surface of the metal foil of the present invention will be described with reference to FIG. Fig.6 (a) is a top view which shows an example of the image formation product produced by the 5th embodiment of the image formation method to the metal foil surface of this invention. FIG. 6B is an enlarged cross-sectional view showing an example of an image forming product manufactured by the fifth embodiment of the image forming method on the surface of the metal foil of the present invention. In the description of the fifth embodiment, the description of the same parts as those in the first to fourth embodiments will be omitted, and different parts will be mainly described.

  The image 8b formed by the image forming method on the surface of the metal foil of the fifth embodiment is the point where the unevenness due to the halftone dots is reversed, leaving the halftone dots 5b as convex portions, and the periphery is etched to form concave portions. This is different from the first to fourth embodiments. In the image 8b of this embodiment, only the halftone dots 5b are convex portions, and the area of the concave portions is larger than that of the halftone dots 5 in FIG. For this reason, the contrast with respect to a non-image part increases further than the image 8 formed in the 1st embodiment. Here, when the ratio of the etched portion in the low reflection portion 6b is the etching area ratio, 80% or more is preferable, 90% or more is more preferable, and 99% or more is still more preferable in order to obtain a desired contrast.

  In addition, as shown in FIGS. 7A to 7E, such etching is performed, for example, by reversing the negative / positive of the photomask used for manufacturing the mask 7 from FIG. As shown in (d) to (d), the resist film is left on the halftone dot forming position and the periphery thereof is etched. As described in the first embodiment, the etching area can be set in consideration of over etching and under etching. In this specification, the negative type photomask refers to a photomask in which the penetrating portion 71 is formed at the halftone dot formation position in the mask 7, and the positive type photomask refers to the halftone dot formation in the mask 7. This is a photomask in which a mask 7 made of a resist film is left at a position and a penetrating portion 72 is formed in other portions. That is, in the first to fourth embodiments described above (halftone dots 5 and 5a are concave portions), a negative photomask is used, and the fifth embodiment and the sixth embodiment described later are used. In (the halftone dots 5b and 5c are convex portions), a positive type photomask is used.

<Sixth embodiment>
Next, an image forming product 1c produced by the sixth embodiment of the image forming method on the metal foil surface of the present invention will be described with reference to FIG. FIG. 8A is a plan view showing an example of an image-formed product produced by the sixth embodiment of the image forming method on the surface of the metal foil of the present invention. FIG.8 (b) is an expanded sectional view which shows an example of the image formation product produced by the 6th embodiment of the image formation method to the metal foil surface of this invention.

  The image 8c formed by the image forming method on the surface of the metal foil of the sixth embodiment has a halftone dot 5c obtained by further etching the top of the convex portion of the halftone dot into a curved surface in addition to the concave portion formation of the fifth embodiment. It is what. That is, the entire surface of the low reflection portion 6c of the image portion 8c is etched, and the non-penetrating unevenness is formed. The etching area ratio of the low reflection portion 6c is 100%. Thereby, the contrast can be further increased. Such etching can be formed by adjusting the mask diameter and pitch in the fifth embodiment and over-etching the mask diameter. The upper limit of overetching is up to the point where the recess does not penetrate the metal foil.

<Modification>
While the present invention has been specifically described with reference to the first to sixth embodiments, the present invention is not limited to the above-described embodiments, and may be modified as appropriate within the scope of the configuration of the present invention. Can be added.

  For example, in the above embodiment, the halftone dot 5 is formed in a substantially perfect circle shape, but the halftone dot 5 may be formed in a polygonal shape such as a quadrangle.

  Further, in the above embodiment, the outer peripheral through portion 4 is formed around the image portion, and the image portion and the non-image portion are partitioned. However, the outer peripheral through portion 4 is not formed, and a low dot that is a set of halftone dots 5 is formed. You may form an image by the reflection parts 6 and 6a.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

[Example 1]
An ultraviolet curable negative resist (manufactured by Hitachi Chemical Co., Ltd.) is applied over the entire surface of a square copper foil having a thickness of 35 μm and a side of 3 cm laminated on the surface of the base material to a thickness of 15 μm. A photomask was used to expose and develop a portion other than the halftone portion, and a mask made of a patterned resist film having the halftone portion as a penetrating portion was produced. The mask was formed as a square with a side of 2 cm, a penetrating part having a diameter of 50 μm was provided as a pattern over the entire surface, and the distance between the center of the penetrating part and the center of the penetrating part was 60 μm. In addition, the penetration part was formed so that it might be what is called closest packing in which all three adjacent penetration parts form a regular triangle with a side of 60 μm. Moreover, the mask was arrange | positioned so that it might be located in the center part of a copper foil surface. An etching solution (product name: iron chloride, manufactured by Tsurumi Soda Co., Ltd.) was exposed to the copper foil with a mask formed on the surface by spraying (liquid temperature 50 ° C., 2 minutes) to etch the surface of the copper foil. . Thereafter, the mask was removed using a caustic soda remover (manufactured by Tsurumi Soda Co., Ltd.) to obtain the image forming product of Example 1. The image-formed product of Example 1 is patterned into a 2 cm square (low reflection portion) smaller than the original copper foil, and has a diameter of 100 μm and a depth corresponding to the position of the through hole provided in the mask. A dot of 25 μm was formed.

[Example 2]
An image forming product of Example 2 was obtained in the same procedure as in Example 1 except that the diameter of the penetrating portion provided in the mask was 40 μm. The image-formed product of Example 2 is patterned into a 2 cm square that is smaller than the original copper foil, and a halftone dot having a diameter of 60 μm and a depth of 15 μm corresponds to the position of the penetrating portion provided in the mask. Was formed.

[Example 3]
After etching the surface of the copper foil, an alkaline blackening solution (manufactured by Nihon Parkerizing Co., Ltd.) is exposed to the copper foil with the mask formed by immersion (liquid temperature 60 ° C., 1 minute), and black The image forming product of Example 3 was obtained in the same procedure as in Example 1 except that the masking process was performed and then the mask was removed. The image-formed product of Example 3 is patterned into a 2 cm square that is smaller than the original copper foil, and a halftone dot having a diameter of 100 μm and a depth of 25 μm corresponds to the position of the through-hole provided in the mask. Was formed.

[Example 4]
In Example 1, a positive type photomask is used instead of a negative type photomask, and a through portion and a non-through portion of a mask made of a resist film are reversed, and a non-through portion having a diameter of 60 μm is used as a mask (resist The image forming product of Example 4 is obtained in the same manner as in Example 1 except that the distance between the center of the non-penetrating part and the center of the non-penetrating part (interval between the centers of the halftone dots) is 80 μm. It was. The image-formed product of Example 4 is patterned into a 2 cm square smaller than the original copper foil (low reflection part), and the non-etched part corresponds to the position of the non-penetrating part provided in the mask. A convex part having a diameter of 15 to 24 μm and a copper foil thickness (height) of 35 μm and a non-penetrating unevenness formed by an etching concave part having a minimum copper foil thickness of 8 μm (maximum depth of 27 μm) were formed around the convex part.

[Example 5]
In Example 4, a non-penetrating portion having a diameter of 40 μm was provided in the mask as a pattern, and the distance between the center of the non-penetrating portion and the center of the non-penetrating portion (interval between the centers of halftone dots) was set to 60 μm. In the same manner as described above, an image forming product of Example 5 was obtained. The image-formed product of Example 5 is patterned into a 2 cm square that is smaller than the original copper foil (low reflection portion), and the top portion is etched corresponding to the position of the non-penetrating portion provided in the mask. The protrusions having a copper foil thickness (height) of 13 μm were formed, and non-penetration irregularities were formed around the protrusions by etching recesses having a copper foil thickness of 8 μm minimum (depth maximum 5 μm).

[Example 6]
In Example 4, a non-penetrating portion having a diameter of 50 μm is provided as a pattern, the interval between the center of the non-penetrating portion and the center of the non-penetrating portion (interval between the centers of halftone dots) is 60 μm, and the shape of the non-penetrating portion is 50 μm. An image-formed product of Example 6 was obtained in the same manner as in Example 4 except that the corner was square. The image-formed product of Example 6 is patterned into a 2 cm square smaller than the original copper foil (low reflection portion), and the top portion is etched corresponding to the position of the non-penetrating portion provided in the mask. The protrusions having a copper foil thickness (height) of 14 μm and non-penetration unevenness formed by etching recesses having a copper foil thickness of 10 μm minimum (depth of 4 μm maximum) were formed around the protrusion.

[Comparative Example 1]
As shown in FIG. 9, a through part having a width of 500 μm was formed around a 2 cm square on a square copper foil having a thickness of 50 μm and a side of 3 cm laminated on the surface of the base material (image formation of Comparative Example 1). ) Product.

  About Example and the comparative example, when the difference (surface contrast) of the surface reflectance of an image part and its circumference | surroundings was compared visually, Example 6> Example 5> Example 4> Example 3> in an order favorable. The order of Example 1> Example 2> Comparative Example 1 was confirmed, and the effects of the present invention were confirmed.

  Further, the image-formed product of Example 3 subjected to the blackening treatment showed good solder suitability as in Examples 1 and 2 and Comparative Example 1, and therefore solder suitability due to the blackening treatment being performed. It was confirmed that there was no effect on.

  As described above, according to the image forming method on the surface of the metal foil of the present invention, the image is formed by patterning on the metal foil itself and non-penetrating halftone dots on the surface of the metal foil by one etching operation. Can be formed. Further, it is understood that an image formed by a set of non-penetrating halftone dots is suitable for identifying an image by visual observation or an automatic identification device because the reflectance is lower than the non-image portion and the contrast is increased.

DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c Image formation product 2 Base material 3 Metal foil 31 Blackening part 4 Perimeter penetration part 5, 5a, 5b, 5c Halftone dot 6, 6a, 6b, 6c Low reflection part 7 Resist film (mask)
71, 72 Penetration part 8, 8a, 8b, 8c Image

Claims (8)

  By forming halftone dots in a desired region on the surface of the metal foil having a predetermined reflectivity and etching the halftone dot portion and / or the periphery thereof, the non-penetrating irregularities having the halftone dot portion as convex portions or concave portions. And forming an image portion having a reflectance lower than the predetermined reflectance in the desired region by the unevenness.   The image forming method on the surface of the metal foil according to claim 1, wherein the image portion is formed by etching the periphery of the halftone dot portion to make the halftone dot portion a convex portion.   The image forming method on the surface of the metal foil according to claim 2, wherein a top portion of the convex portion has a curved surface.   The image forming method on the surface of the metal foil according to claim 1, wherein the image portion is a predetermined surface pattern.   The image forming method on the metal foil surface according to any one of claims 1 to 3, wherein the image portion is a product information code. A mask forming step of forming a mask having a dot-like through portion on the surface of the metal foil using a resist;
A half-etching step in which a halftone dot, which is a recess that does not penetrate the metal foil, is formed by etching on the surface of the metal foil using the mask;
The image forming method on the metal foil surface according to any one of claims 1 to 5, further comprising: a mask removing step of removing the mask from the surface of the metal foil subjected to the half etching step. In the mask formation step, in addition to the dot-shaped through portion, a mask having a through portion for further patterning the metal foil itself is formed,
7. The image formation on the surface of the metal foil according to claim 6, wherein in the half etching step, the metal foil is patterned and the image portion is simultaneously formed by simultaneously patterning the metal foil itself. Method.   Between the half-etching step and the mask removing step, the inside of the halftone dots formed in the half-etching step is further blackened by a blackening agent that blackens the surface of the metal constituting the metal foil. The image formation method to the metal foil surface of Claim 6 or 7 which has the blackening process to make.

Images