Method for manufacturing wiring board, and wiring board

Abstract

This method for manufacturing a printed wiring board 1 comprises: a preparation step for preparing a base film 10 on which a wiring pattern 20 is disposed; a peeling layer disposal step for disposing a slightly adhesive film 40 on the base film 20 so as to cover a portion of the wiring pattern 20; a coverlay formation step for disposing a coverlay 30 on the base film 10 so as to cover the wiring pattern 20 and the slightly adhesive film 40; and a peeling step in which peeling the slightly adhesive film 40 from the base film 10 and simultaneously removing a removal section 301, which is the portion of the coverlay 30 stacked on the slightly adhesive film 40, thereby exposing a portion of the wiring pattern 20 from the coverlay 30.

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing a wiring board, and to a wiring board. For designated states in which incorporation by reference of literature is permitted, the contents of Patent Application No. 2021-010413 filed in Japan on January 26, 2021 are incorporated by reference into this specification and made a part of the description of this specification. [Background technology]

[0002] A manufacturing method for a flexible printed circuit (FPC) is known in which an opening formed in a coverlay film is positioned relative to a terminal portion of a conductor pattern by inserting a positioning pin into a positioning hole provided in the coverlay film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2005-327982 A Summary of the Invention [Problem to be solved by the invention]

[0004] When manufacturing a long FPC, it is necessary to use a long coverlay film. Because the coverlay film is thin and soft, the longer it is, the more difficult it becomes to handle and the greater the dimensional variation. For this reason, with the above method, it is difficult to precisely align the position of the opening in the coverlay film with respect to the base film, which creates the problem that the terminals may not be formed with precision.

[0005] An object of the present invention is to provide a method for manufacturing a wiring board that is capable of forming terminal portions with high precision. [Means for solving the problem]

[0006] [1] A method for manufacturing a wiring board in the present invention is a method for manufacturing a wiring board comprising a substrate, wiring arranged on the substrate, and a coverlay laminated on the substrate to cover the wiring, the method comprising: a first step of preparing the substrate on which the wiring is arranged; a second step of arranging a release layer on the substrate to cover a portion of the wiring; a third step of arranging a coverlay on the substrate to cover the wiring and the release layer; and a fourth step of peeling the release layer from the substrate to remove a portion of the coverlay that is laminated on the release layer and expose a portion of the wiring from the coverlay.

[0007] [2] In the above invention, the release layer is a weakly adhesive film having a peel strength to the substrate that is smaller than the peel strength of the coverlay to the substrate, and the second step may include attaching the weakly adhesive film to the substrate so as to cover a portion of the wiring.

[0008] [3] In the above invention, the fourth step may include peeling the release layer from the base material while a portion of the coverlay other than the portion to be removed is held down by a holding means.

[0009] [4] In the above invention, the method for manufacturing a wiring board may further include a fifth step, prior to the fourth step, of exposing the release layer from an end of the wiring board by cutting the coverlay, the release layer, and the base material.

[0010] [5] In the above invention, the method for manufacturing a wiring board may include, after the fourth step, a sixth step of covering, with a resin material, an edge of the coverlay from which the removed portion has been removed.

[0011] [6] The longitudinal length of the wiring board may be 600 mm or more.

[0012] [7] The wiring board of the present invention comprises a substrate, wiring arranged on the substrate, and a coverlay laminated on the substrate so as to cover the wiring, wherein an open portion is formed in the coverlay to expose a portion of the wiring, and the coverlay has a burr along the edge of the coverlay that is not in contact with the substrate.

[0013] [8] In the above invention, the wiring board may include a resin material covering the edge portion.

[0014] [9] In the above invention, the length of the wiring board in the longitudinal direction may be 600 mm or more. Effect of the Invention

[0015] In the present invention, a coverlay is laminated on top of a release layer disposed so as to cover the wiring on the substrate, and the release layer is peeled off to expose the wiring and form the terminal portion. Since the release layer only needs to be disposed on the portion of the wiring that corresponds to the terminal portion, the coverlay can be positioned with high positional accuracy relative to the substrate regardless of its size. Therefore, in the present invention, the terminal portion can be formed with high accuracy. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a plan view showing a printed wiring board in an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view showing the printed wiring board in the embodiment of the present invention, taken along line II-II in FIG. [Diagram 3] 3(a) to 3(h) are cross-sectional views illustrating a method for manufacturing a printed wiring board in an embodiment of the present invention. [Figure 4] FIG. 4(a) is a plan view corresponding to FIG. 3(b), and FIG. 4(b) is a plan view corresponding to FIG. 3(b) as well as a diagram illustrating a modified example of the method for manufacturing a printed wiring board in an embodiment of the present invention. [Diagram 5]FIG. 5 is a cross-sectional view showing a modified example of the printed wiring board according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0018] FIG. 1 is a plan view showing a printed wiring board according to the embodiment of the present invention.

[0019] The printed wiring board 1 in this embodiment is a flexible printed circuit board (FPC) having an overall long rectangular shape. Although not particularly limited, the length L along the longitudinal direction (X direction in the figure) of the printed wiring board 1 is 600 mm to 5000 mm (600 mm ≦ L ≦ 5000 mm), and the width W along the short side direction (Y direction in the figure) of the printed wiring board 1 is 1 mm to 250 mm (1 mm ≦ W ≦ 250 mm).

[0020] The planar shape of the printed wiring board 1 is not limited to a rectangular shape only, and any shape can be selected. For example, it may partly have a branched shape extending in multiple branches. Also, the width of the printed wiring board 1 does not have to be constant throughout the longitudinal direction, and the width of the printed wiring board 1 may be wider or narrower in a part of the longitudinal direction.

[0021] Alternatively, the printed wiring board 1 may have a large rectangular planar shape by having a width W wider than 250 mm (250 mm < W ≦ 1000 mm). Note that the planar shape of the large printed wiring board is not particularly limited to the above and can be any shape. At this time, it is sufficient that a virtual rectangle circumscribing the planar shape of the large printed wiring board has the above length L and width W.

[0022] The printed wiring board 1 having such a long or large planar shape is used, for example, in applications such as automobiles, industrial machines, and medical devices. Note that the usage of the printed wiring board 1 in this embodiment is not particularly limited.

[0023] 2, the printed wiring board 1 includes a base film 10, a wiring pattern 20, and a coverlay 30. The base film 10 in this embodiment corresponds to an example of the "substrate" in the present invention, the wiring pattern 20 in this embodiment corresponds to an example of the "wiring" in the present invention, and the coverlay 30 in this embodiment corresponds to an example of the "coverlay" in the present invention.

[0024] The base film 10 is a flexible film having a long strip shape. The base film 10 is made of an electrically insulating material such as a resin material. Although not particularly limited, examples of the material constituting the base film 10 include polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyetherimide (PEI), polyether ether ketone (PEEK), and aramid.

[0025] A plurality of wiring patterns 20 are formed on the base film 10. The wiring patterns 20 are made of a conductive material such as metal or carbon. Examples of metals constituting the wiring patterns 20 include copper, silver, and gold. In this embodiment, copper is used as the material constituting the wiring patterns 20. The number of wiring patterns 20 is not limited to a plurality, and may be one.

[0026] In this embodiment, as shown in FIG. 1, a plurality of wiring patterns 20 having the same length extend linearly along the X direction on the base film 10. The plurality of wiring patterns 20 are arranged parallel to each other at equal intervals. The plurality of wiring patterns 20 are arranged so that their positions in the X-axis direction are equal to each other. The number, shape, arrangement, etc. of the wiring patterns 20 are not particularly limited to this and can be set arbitrarily. In addition, the wiring patterns may be formed on both sides of the base film 10, and the wiring patterns may include via holes, etc.

[0027] 1, terminal portions 21 are formed on both ends of each wiring pattern 20. For example, connectors provided on other printed wiring boards or cables are connected to these terminal portions 21, and the printed wiring board 1 is electrically connected to an external electronic circuit via these terminal portions 21. Note that the positions at which the terminal portions 21 are formed are not limited to the ends of the wiring pattern 20, and any positions on the wiring pattern 20 can be selected. Furthermore, the number of terminal portions 21 on the wiring pattern 20 is not particularly limited.

[0028] 2, the coverlay 30 has a two-layer structure consisting of a protective layer 31 and an adhesive layer 32. The coverlay 30 has an open portion 33 formed by removing an end portion of the coverlay 30, and the terminal portion 21 of the wiring pattern 20 is exposed from this open portion 33. The coverlay 30 also has a burr 34 formed on an edge portion along the open portion 33. The open portion 33 in this embodiment corresponds to an example of an "open portion" in the present invention, and the burr 34 in this embodiment corresponds to an example of a "burr" in the present invention.

[0029] The protective layer 31 is a layer for protecting the wiring pattern 20. The protective layer 31 is made of a flexible film having a long band shape. The protective layer 31 is made of an electrically insulating material such as a resin material. Although not particularly limited, examples of the material constituting the protective layer 31 include polyimide (PI), liquid crystal polymer (LCP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyetherimide (PEI), polyether ether ketone (PEEK), and aramid.

[0030] The adhesive layer 32 is a layer for adhering the protective layer 31 to the upper surface of the base film 10. The adhesive layer 32 is made of, for example, an epoxy adhesive or an acrylic adhesive.

[0031] The material constituting the coverlay 30 is not particularly limited to the above. For example, the coverlay 30 may be formed using a dry film made of a photosensitive coverlay material instead of the above-mentioned resin film, or the coverlay 30 may be formed by applying a liquid photosensitive coverlay material onto the base film 10, followed by exposure and development. Alternatively, the coverlay 30 may be formed by printing a liquid coverlay ink onto the base film 10.

[0032] Alternatively, the coverlay 30 may be made of so-called solder resist. Specifically, the coverlay 30 may be formed using a dry film made of a photosensitive resist material. Alternatively, the coverlay 30 may be formed by applying a liquid photosensitive resist material onto the base film 10, followed by exposure and development. Alternatively, the coverlay 30 may be formed by printing a liquid solder resist ink onto the base film 10.

[0033] Specific examples of the above-mentioned photosensitive coverlay material and photosensitive resist material include those using polyester, epoxy, acrylic, polyimide, polyurethane, etc. Specific examples of the above-mentioned coverlay ink and solder resist ink include those based on polyimide or epoxy.

[0034] Burrs 34 are portions formed incidentally when coverlay 30 is cut in a manufacturing method for printed wiring board 1, which will be described later. Burrs 34 protrude from main body portion 302 of coverlay 30 adhered to base film 10, float above base film 10, and are not adhered to base film 10.

[0035] Hereinafter, the method for manufacturing the printed wiring board 1 in this embodiment will be described with reference to Figs. 3(a) to 3(h), 4(a) and 4(b). Figs. 3(a) to 3(h) are cross-sectional views showing the method for manufacturing the printed wiring board in this embodiment. Fig. 4(a) is a plan view corresponding to Fig. 3(b). Fig. 4(b) is a plan view corresponding to Fig. 3(b) and shows a modified example of the method for manufacturing the printed wiring board in this embodiment.

[0036] First, as shown in Fig. 3(a), a base film 10 on which one or more wiring patterns 20 are formed is prepared on a jig 100 (preparation step). The method for forming the wiring pattern 20 on the base film 10 is not particularly limited, but examples include a subtractive method and a semi-additive method. The preparation step in this embodiment corresponds to an example of the "first step" in the present invention.

[0037] Next, as shown in FIG. 3(b), a rectangular-shaped micro-adhesive film 40 is placed on the base film 10 so as to cover a part of the wiring pattern 20 (peeling layer placement process). Specifically, as shown in FIG. 4(a), the micro-adhesive film 40 is placed across the multiple wiring patterns 20 so as to cover a part of each wiring pattern 20. At this time, the micro-adhesive film 40 is placed so that the long side of the micro-adhesive film 40 is perpendicular to each wiring pattern 20. The peeling layer placement process in this embodiment corresponds to an example of the "second process" in the present invention. Note that, as shown in FIG. 4(b), multiple micro-adhesive films 40 may be placed individually with respect to multiple wiring patterns 20 so that one micro-adhesive film 40 covers only one wiring pattern 20.

[0038] Although not particularly shown, the weakly adhesive film 40 can be positioned on the base film 10 by inserting a positioning pin provided on the base film 10 into a through hole formed in the weakly adhesive film 40. The weakly adhesive film 40 may also be positioned by image recognition.

[0039] As shown in Fig. 3(b), the weak adhesive film 40 has a structure in which a substrate 41 and an adhesive layer 42 are laminated. In the peeling layer arrangement step, the weak adhesive film 40 is arranged on the base film 10 so that the adhesive layer 42 contacts the base film 10. The material constituting the substrate 41 of the weak adhesive film 40 is not particularly limited, but polyester can be exemplified. The adhesive layer 42 of the weak adhesive film 40 is not particularly limited, but an acrylic adhesive can be exemplified.

[0040] The peel strength of such a weak adhesive film 40 to the base film 10 is weaker than the peel strength of the adhesive layer 32 to the base film 10 when measured under the same conditions. Examples of a method for testing the peel strength include the 90-degree peel test specified in JIS K 6854-1 and JIS Z 0237.

[0041] As long as the above peel strength relationship is satisfied, the material constituting the weak adhesive film 40 is not particularly limited to the above. In addition, instead of the weak adhesive film 40, a resin material may be applied onto the base film 10 so as to cover a part of the wiring pattern 20, and the resin material may be cured to form a peel layer.

[0042] 3(c), the coverlay 30 is placed on the base film 10 so as to cover the wiring pattern 20 and the weak adhesive film 40, and the adhesive layer 32 is brought into contact with the base film 10 (coverlay formation process). At this time, the adhesive layer 32 does not come into contact with the portion of the wiring pattern 20 where the weak adhesive film 40 is placed.

[0043] The size and shape of the coverlay 30 are not limited as long as the coverlay 30 has a size that can cover the wiring pattern 20 and the weak adhesive film 40. With the coverlay 30 pressed against the base film 10, the entire coverlay 30 is heated to harden the adhesive layer 32 and bond the protective layer 31 to the base film 10. The coverlay formation step in this embodiment corresponds to an example of the "third step" in the present invention.

[0044] Next, as shown in FIG. 3(d), the coverlay 30 and the base film 10 are cut using a mold 70 for contour processing according to the contour shape of the printed wiring board 1 to be manufactured (contour forming process). At this time, as shown in FIG. 3(d) and FIG. 3(e), the coverlay 30 and the base film 10 are cut including the weak adhesive film 40 at the location where the weak adhesive film 40 is laminated, and the end face of the weak adhesive film 40 is exposed in the X-axis direction from the coverlay 30. The contour forming process in this embodiment corresponds to an example of the "fifth process" in the present invention. The contour forming method of the printed wiring board 1 is not particularly limited to the above, and for example, the contour forming of the printed wiring board 1 may be performed using a laser.

[0045] In addition, in the above-mentioned peel-off layer placement process, if the micro-adhesive film 40 is placed on the base film 10 so that the end face of the micro-adhesive film 40 or a portion of the micro-adhesive film 40 is exposed from the printed wiring board 1, this contour formation process may be omitted.

[0046] 3(f), the weak adhesive film 40 and the portion of the coverlay 30 laminated to the weak adhesive film 40 are peeled off from the base film 10. At this time, since the peel strength of the weak adhesive film 40 to the base film 10 is weaker than the peel strength of the adhesive layer 32 to the base film 10, only the weak adhesive film 40 is peeled off from the base film 10, and the adhesive layer 32 is not peeled off from the base film 10.

[0047] 3(g) and 3(h), a plate-shaped pressing jig 50 is placed on the main body portion 302 of the coverlay 30 other than the removal portion 301 laminated on the weak adhesive film 40, and the main body portion 302 is pressed against the base film 10. With the main body portion 302 pressed by the pressing jig 50, the removal portion 301 and the weak adhesive film 40 are pressed against the pressing jig 50 to separate the removal portion 301 and the weak adhesive film 40 from the main body portion 302 (peeling process). Note that the pressing jig 50 is not particularly limited to this, and may be a cutting tool such as the blade of a cutter knife.

[0048] As a result, an open portion 33 is formed in the coverlay 30 where the removed portion 301 was previously present. A part of the wiring pattern 20 is exposed from the open portion 33, forming a terminal portion 21. A portion of the coverlay 30 that has been peeled off together with the weak adhesive film 40 but not cut off from the main body portion 302 is formed as the above-mentioned burr 34. The removed portion 301 in this embodiment corresponds to an example of the "removed portion" in the present invention, the peeling step in this embodiment corresponds to an example of the "fourth step" in the present invention, and the pressing jig 50 in this embodiment corresponds to an example of the "pressing means" in the present invention.

[0049] In this peeling step, the timing of peeling the weakly adhesive film 40 from the base film 10 and the timing of cutting off the removed portion 301 of the coverlay 30 while it is held down by the holding jig 50 may be substantially simultaneous. Specifically, the holding jig 50 may be placed on the main body portion 302 of the coverlay 30, and while the main body portion 302 is held down by the holding jig 50, the weakly adhesive film 40 may be peeled off from the base film 10, and at the same time, the removed portion 301 of the coverlay 30 and the weakly adhesive film 40 may be cut off from the main body portion 302.

[0050] Furthermore, if the removed portion 301 of the coverlay 30 can be separated without using the pressing jig 50, the pressing jig 50 does not need to be used in this peeling step.

[0051] Finally, the pressing jig 50 is removed from the coverlay 30. In this manner, the printed wiring board 1 of the present embodiment is manufactured.

[0052] In the manufacturing method of the printed wiring board 1 in this embodiment, the coverlay 30 is laminated on top of the weak adhesive film 40 arranged so as to cover the wiring pattern 20 on the base film 10, and the weak adhesive film 40 is peeled off to expose the wiring pattern 20 and form the terminal portion 21. This weak adhesive film 40 only needs to be arranged on the parts of the wiring pattern 20 that correspond to the terminal portion 21, so it can be arranged with high positional accuracy with respect to the base film 10 regardless of the size of the coverlay 30. Therefore, the terminal portion 21 can be formed with high accuracy.

[0053] In particular, when manufacturing long printed wiring boards, it is difficult to handle the coverlay, which is made of a thin and soft material, and the effect of dimensional errors in the base film becomes significant. This makes it difficult to accurately align the coverlay with the base film, which may reduce the productivity of printed wiring boards and cause defects in appearance such as creases and wrinkles in the coverlay.

[0054] In contrast, in the method for manufacturing the printed wiring board 1 in this embodiment, the coverlay 30 having no openings is simply laminated on the base film 10, and then the coverlay 30 and the base film 10 are cut to form the outer shape. Therefore, there is no need to accurately align the coverlay 30 with the base film 10. Therefore, even when manufacturing a long printed wiring board 1, it is possible to suppress a decrease in the productivity of the printed wiring board 1 and to suppress the occurrence of defects in the appearance of the coverlay 30.

[0055] In this embodiment, the lengths of the multiple wiring patterns 20 are equal, and the individual wiring patterns 20 are disposed at equal positions in the X-axis direction. Therefore, as shown in FIG. 4(a), the rectangular-shaped weak adhesive film 40 is disposed so as to straddle the individual wiring patterns 20 and to be perpendicular to the individual wiring patterns 20, so that the terminal portions 21 of the same shape can be formed for the individual wiring patterns 20. That is, by disposing the weak adhesive film 40 once, the terminal portions 21 of the multiple wiring patterns 20 can be formed at once. Therefore, compared to the case where one weak adhesive film 40 is disposed on one wiring pattern 20, the workability is improved.

[0056] FIG. 5 is a cross-sectional view showing a modified example of the printed wiring board in this embodiment.

[0057] 5, the printed wiring board 1 in this embodiment may have a sealing resin 60 formed so as to cover the burrs 34 of the coverlay 30. Examples of materials constituting the sealing resin 60 include epoxy resin, acrylic resin, polyester resin, urethane resin, vinyl resin, silicone resin, phenolic resin, polyimide resin, etc. The sealing resin 60 in this embodiment corresponds to an example of the "resin material" in the present invention.

[0058] To form the sealing resin 60, in the method for manufacturing the printed wiring board 1 in this embodiment, after the peeling step, a sealing resin material is applied using a dispenser or the like so as to cover the burrs 34. The applied sealing resin material is cured to form the sealing resin 60 (sealing resin forming step). The sealing resin forming step in this embodiment corresponds to an example of the sixth step in the present invention.

[0059] 5, the printed wiring board 1 is provided with the sealing resin 60, so that the space between the burr 34 and the base film 10 is filled with the sealing resin 60. This prevents the plating solution from flowing between the burr 34 and the base film 10 when plating the terminal portion 21 in a later process. This prevents the plating solution from flowing into the space between the burr 34 and the base film 10 and causing liquid stains, and prevents the occurrence of defective appearance of the printed wiring board 1.

[0060] The above-described embodiments are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is intended to include all design modifications and equivalents that fall within the technical scope of the present invention. [Explanation of symbols]

[0061] 1...Printed wiring board 10...Base film 20...Wiring pattern 21...Terminal section 30…Coverlay 31...Protective layer 32...adhesive layer 33...Open part 34…Bali 301...Removed part 302…Body part 320…Adhesive 40...Slightly adhesive film 50…Pressing tool 60…Sealing resin 70…Mold 100…Jig

Claims

1. A method for manufacturing a wiring board including a base material, wiring arranged on the base material, and a coverlay laminated on the base material so as to cover the wiring, comprising: A first step of preparing the base material on which the wiring is disposed; a second step of disposing a release layer on the substrate so as to cover a portion of the wiring; a third step of disposing a coverlay on the substrate so as to cover the wiring and the release layer; a fourth step of removing a removal portion of the coverlay laminated on the release layer by peeling the release layer from the base material, thereby exposing a part of the wiring from the coverlay; The fourth step is a method for manufacturing a wiring board, the method including: pressing the portion of the coverlay other than the portion to be removed against a pressing means while pressing the portion to be removed, thereby peeling the release layer off from the base material, and removing the portion of the coverlay where the release layer is not laminated by cutting.

2. 2. A method for manufacturing a wiring board according to claim 1, comprising the steps of: the release layer is a weakly adhesive film having a peel strength of the release layer to the substrate that is smaller than a peel strength of the coverlay to the substrate; The second step of the method for manufacturing a wiring board includes attaching the low-pressure adhesive film onto the base material so as to cover a portion of the wiring.

3. A method for manufacturing a wiring board according to claim 1 or 2, comprising the steps of: The method for manufacturing a wiring board further includes a fifth step, prior to the fourth step, of exposing the release layer from an end of the wiring board by cutting the coverlay, the release layer, and the base material.

4. A method for producing a wiring board according to any one of claims 1 to 3, The method for manufacturing a wiring board includes, after the fourth step, a sixth step of covering, with a resin material, the edge of the coverlay from which the removed portion has been removed.

5. A substrate; Wiring disposed on the substrate; a coverlay laminated on the base material so as to cover the wiring; an opening portion that exposes a part of the wiring is formed in the coverlay, The coverlay includes a protective layer and an adhesive layer that adheres the protective layer to the base material, the coverlay has a burr at an edge of the coverlay along the open portion that is not in contact with the substrate; an end surface of the adhesive layer facing the open portion is in contact with the wiring; A wiring board, wherein an end portion of the adhesive layer constituting the burr is located outside the end surface of the adhesive layer.

6. 6. The wiring board according to claim 5, The wiring board includes a resin material covering the edge portion.

Images