JP2015012099A - Flexible printed wiring board and method for manufacturing flexible printed wiring board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wiring board which can appropriately accommodate to various substrate shapes and bent shapes and can maintain the bent shape for a long period of time so as to be advantageous in cost, and to provide a method for manufacturing the wiring board.SOLUTION: A flexible printed wiring board includes a laminated body having at least one or more substrates containing a base film having a flexibility and one or more conductive patterns laminated on one side or both sides of the base film, in which the laminated body has one or more recess portions for folding the laminated body. It is preferable for the laminated body to include a cover film which covers at least one conductive pattern of one or more conductive patterns. The recess portion is preferably formed on the cover film or the base film. The cover film or the base film is preferably made of a liquid crystal polymer as a main component.

Description

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

  In recent years, flexible printed wiring boards have been used for wiring and the like in the electronic equipment field. This flexible printed wiring board has a substrate in which a conductive pattern is laminated on at least one surface side of a base film. The conductive pattern is usually covered with a protective film. Such a flexible printed wiring board is required not only to have flexibility, but also to be able to maintain the bent shape for a long period of time depending on the application and the location of placement.

  The flexible printed wiring board is bent, for example, by placing a blade at a bending position with the flexible printed wiring board set on a bending jig and attaching a bending ridge to the flexible printed wiring board starting from the blade. However, the substrate is made flexible by the base film. For this reason, the crease attached to the substrate tends to weaken with time, and it is difficult to maintain the desired bent shape for a long period of time by the method of attaching the bending crease to the substrate.

  On the other hand, it has been proposed to use a fixture to maintain the bent state of the flexible flat cable (Japanese Patent Application Laid-Open No. 2010-010198).

JP 2010-010198 A

  If the fixing tool is used, it is easy to maintain the bent shape of the substrate for a long time. However, since the fixture is composed of a plurality of resin molded products having complicated shapes, it is not only easy to attach the fixture, but it may be disadvantageous in terms of manufacturing cost. Also, if the flexible printed wiring board substrate (base film) has a different shape or bent shape, it may be necessary to use a mold according to the shape. There is.

  The present invention has been made based on the above-described circumstances, and provides a flexible printed wiring board that can appropriately cope with various substrate shapes and bent shapes and can maintain the bent shapes for a long period of time in an advantageous cost manner. The purpose is that.

The invention made to solve the above problems is
A flexible printed wiring board comprising a laminate having at least one or more substrates including a flexible base film and one or more conductive patterns laminated on one or both sides of the base film. ,
The said laminated body has 1 or several recessed part for bending this laminated body.

Another invention made to solve the above problems is as follows:
Method for forming flexible printed wiring board comprising a laminate having at least one or a plurality of substrates including a flexible base film and one or a plurality of conductive patterns laminated on one or both sides of the base film Because
Forming one or a plurality of recesses for folding the laminate.

  ADVANTAGE OF THE INVENTION According to this invention, the flexible printed wiring board which can maintain the bending shape of a flexible printed wiring board easily for a long period of time, can respond appropriately to various board | substrate shapes and bending shapes advantageously, and its manufacturing method are provided. .

1 is a schematic plan view showing a flexible printed wiring board according to a first embodiment of the present invention. It is typical sectional drawing which follows the X1-X1 line | wire of FIG. It is typical sectional drawing which follows the X2-X2 line | wire of FIG. It is typical sectional drawing which follows the X3-X3 line | wire of FIG. It is typical sectional drawing which expands and shows the principal part of FIG. It is typical sectional drawing which shows the state which bent the flexible printed wiring board of FIG. It is a typical top view equivalent to Drawing 1 showing the flexible printed wiring board concerning a 2nd embodiment of the present invention. It is typical sectional drawing which follows the X4-X4 line | wire of FIG. It is typical sectional drawing which follows the X5-X5 line | wire of FIG. It is a schematic plan view for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention. It is a schematic plan view for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention. It is a schematic plan view for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention. It is typical sectional drawing which follows the X6-X6 line | wire of FIG. It is typical sectional drawing which shows the principal part for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention. It is typical sectional drawing which shows the principal part for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention. It is typical sectional drawing which shows the principal part for demonstrating the recessed part of the flexible printed wiring board which concerns on other embodiment of this invention.

[Description of Embodiment of the Present Invention]
The present invention
A flexible printed wiring board including a laminate having at least one or a plurality of substrates including a flexible base film and one or a plurality of conductive patterns laminated on one side or both sides of the base film. ,
The said laminated body has 1 or several recessed part for bending this laminated body.

  According to the flexible printed wiring board, the laminate (the flexible printed wiring board) can be bent starting from the concave portion. Therefore, the flexible printed wiring board can be easily bent at the target position by using the recess. Moreover, since the laminated body is bent while being partially divided by the concave portions, the bent shape of the flexible printed wiring board can be maintained for a long period of time. Furthermore, since the concave portion can be formed by laser processing, mold formation, or the like, the concave portion can be formed easily and accurately and advantageously in terms of cost.

  The laminate may further include a cover film that covers at least one conductive pattern of one or a plurality of conductive patterns, and the concave portion may be formed in the cover film. Thus, by forming a recessed part in a cover film, a flexible printed wiring board can be bent in the target position from the recessed part of a cover film.

  As the cover film, a film mainly composed of a liquid crystal polymer is preferable. As described above, since the cover film contains the liquid crystal polymer as a main component, the concave portion can be formed easily and accurately by laser processing, pressing a heated mold, or the like.

  The laminate further includes a cover film covering at least one of the one or more conductive patterns, and the base film is exposed at a portion where the one or more conductive patterns are not formed, The concave portion may be formed in an exposed portion of the base film. By forming the recesses in the exposed portions of the base film in this way, it becomes easy to form the recesses in the base film and the flexible printed wiring board is bent at the base film as the core material. The shape can be maintained more appropriately for a long time. Moreover, since the exposed part in a base film is also a part in which the conductive pattern is not formed, a flexible printed wiring board can be bent appropriately, avoiding disconnection of a conductive pattern.

  The depth of the recess is preferably 1/5 or more and 3/4 or less with respect to the thickness of the base film. In the case where the concave portion is formed in the base film, by setting the depth of the concave portion within the above range, the flexible printed wiring board can be more easily bent and the bent shape can be maintained for a long time.

  As said base film, what has a liquid crystal polymer as a main component is preferable. As described above, since the base film contains the liquid crystal polymer as a main component, the concave portion can be easily and accurately formed by laser processing, pressing a heated mold, or the like.

  It is preferable that the concave portion is bent so as to be outside. In this way, the flexible printed wiring board can be bent more easily and the bent shape can be maintained for a long period of time by bending the concave portion outward.

Another invention is
Method for forming flexible printed wiring board comprising a laminate having at least one or a plurality of substrates including a flexible base film and one or a plurality of conductive patterns laminated on one or both sides of the base film Because
Forming one or a plurality of recesses for folding the laminate.

  According to the manufacturing method, a flexible printed wiring board that can be easily bent at a target position starting from the recess is suitably provided. Moreover, since the laminated body is bent in a state in which the laminate is partially divided by the recess, a flexible printed wiring board that can maintain the bent shape for a long period of time is suitably provided.

  The step of forming the recess may be performed by irradiating laser light. Thus, the process of forming the said recessed part is performed by irradiation of a laser beam, and can improve the positional accuracy of a recessed part compared with the conventional bending process.

  The step of forming the recess may be performed by pressing a heated mold. Thus, the process of forming the said recessed part is performed by pressing the heated metal mold | die, and a recessed part can be formed easily and correctly.

  The method further includes a step of laminating a cover film on the substrate so as to cover at least one of the one or more conductive patterns, and the step of forming the concave portion forms the concave portion in the cover film. Is preferably carried out. Thus, by forming a recessed part in a cover film, the flexible printed wiring board which can be bent in the target position from the recessed part of a cover film can be provided.

  The method further includes the step of covering at least one of the one or more conductive patterns and laminating a cover film on the substrate so that a portion where the conductive pattern is not formed is exposed, and forming the recess. It is preferable that a process is performed by forming the said recessed part in the said base film. By forming the recesses in the exposed portions of the base film in this way, it is easy to form the recesses in the base film, and the flexible print that can be bent and maintained in the core film as a core material more appropriately for a long period of time. A wiring board is provided. Moreover, since the exposed part in a base film is also a part in which the conductive pattern is not formed, the flexible printed wiring board which can be bent appropriately, avoiding disconnection of a conductive pattern is provided.

[Details of the embodiment of the present invention]
Hereinafter, a flexible printed wiring board and a manufacturing method thereof according to the present invention will be described in detail with reference to the drawings.

[First Embodiment]
First, the flexible printed wiring board which concerns on the 1st Embodiment of this invention is demonstrated with reference to FIGS.

  The flexible printed wiring board 1 of FIGS. 1 to 4 includes a laminate including a flexible substrate 2 and a pair of cover films 30 and 31 laminated on the substrate 2.

<Board>
The substrate 2 includes a base film 20 and conductive patterns 21 and 22 stacked on the surfaces 20 a and 20 b of the base film 20.

(Base film)
The base film 20 is configured by a sheet-like member having flexibility and electrical insulation. Specifically, a resin film can be adopted as the base film 20. As a material of this resin film, for example, a liquid crystal polymer, a polyimide resin, a polyethylene terephthalate resin, and the like are preferable, and among them, a liquid crystal polymer is more preferable.

  The thickness of the base film 20 is, for example, 10 μm or more and 30 μm or less. If the thickness of the base film 20 is larger than the above range, the strength of the base film 20 may be insufficient. On the other hand, if the thickness of the base film 20 is smaller than the above range, the flexible printed wiring board 1 may be unnecessarily thick.

(Conductive pattern)
The conductive patterns 21 and 22 are composed of a plurality of individual wires 21a and 22a. The conductive patterns 21 and 22 are formed by etching a metal layer laminated on the base film 20. The metal layer forming the conductive patterns 21 and 22 can be formed of a conductive material, but is formed of, for example, copper.

  The method for laminating the metal layer on the base film 20 is not particularly limited. For example, an adhesion method in which a metal foil is bonded with an adhesive, or a casting method in which a resin composition that is a material of the base film 20 is applied onto the metal foil. A sputtering / plating method in which a metal layer is formed by electrolytic plating on a thin conductive layer (seed layer) having a thickness of several nanometers formed on the base film 20 by sputtering or vapor deposition. The law etc. can be used.

  The thickness of the conductive patterns 21 and 22 is, for example, not less than 10 μm and not more than 30 μm. When the thickness of the conductive patterns 21 and 22 is smaller than the above range, the conductivity may be insufficient. On the other hand, if the thickness of the conductive patterns 21 and 22 is larger than the above range, the flexible printed wiring board 1 may impair flexibility.

(Cover film)
The cover films 30 and 31 are laminated on the surfaces 20a and 20b of the base film 20 so as to cover the conductive patterns 21 and 22 via the adhesive layers 32 and 33. The cover films 30 and 31 are formed by laminating most of the conductive pattern patterns 21 and 22 except for the end of the base film 20. The cover films 30 and 31 have two concave portions 34 and 35.

  The material of the cover films 30 and 31 is not particularly limited, and the same resin film as that constituting the base film 20 can be used. Among them, a liquid crystal polymer and a polyimide resin are preferable.

  The thickness of the cover films 30 and 31 is, for example, 10 μm or more and 30 μm. If the thickness of the cover films 30 and 31 is smaller than the above range, the insulation may be insufficient. On the other hand, when the thickness of the cover films 30 and 31 is larger than the said range, there exists a possibility that the flexible printed wiring board 1 may impair flexibility.

  Further, the material of the adhesive layers 32 and 33 is not particularly limited, but is preferably excellent in flexibility and heat resistance, for example, polyimide resin, polyamide resin, epoxy resin, butyral resin, acrylic resin, etc. These are various resin-based adhesives, among which polyimide resin is preferable. Although it does not specifically limit as thickness of the contact bonding layers 32 and 33, 20 micrometers or more and 30 micrometers or less are preferable. If the thickness of the adhesive layers 32 and 33 is smaller than the above range, the adhesion may be insufficient. On the other hand, if the thickness of the adhesive layers 32 and 33 is larger than the above range, the flexible printed wiring board 1 may impair the flexibility.

<Recess>
The recesses 34 and 35 are for bending the flexible printed wiring board 1. The recess 34 is provided in the cover film 30, and the recess 35 is provided in the cover film 31. The recesses 34 and 35 are each formed in a groove shape extending in the width direction of the cover films 30 and 31. As clearly shown in FIG. 4, the cross-sectional shape of these recesses 34 (35) is V-shaped or U-shaped with rounded tips. The depth of the recesses 34 and 35 is, for example, 5 μm or more and 30 μm or less, and preferably 10 μm or more and 20 μm or less.

The recesses 34 and 35 can be formed by molding, laser processing, or the like. Mold molding is performed, for example, by pressing a mold heated to 300 ° C. or higher against the flexible printed wiring board 1. Laser processing can be performed, for example, by irradiating the flexible printed wiring board 1 with laser light from a gas laser. Examples of the gas laser include an excimer laser, a CO ₂ laser, an Ar laser, and a He—Ne laser. The laser processing conditions are, for example, a spot diameter of 0.1 mm to 0.4 mm, a frequency of 50 Hz to 400 Hz, and an irradiation intensity of 5 mJ to 20 mJ. When the cover films 30 and 31 and the base film 20 are formed of a thermoplastic resin such as a liquid crystal polymer, the cover films 30 and 31 and the base film 20 are partially melted by molding and laser processing and then cooled. Recesses 34 and 35 can be formed. By forming the concave portions 34 and 35 by heating, such as laser light irradiation, the positional accuracy can be improved as compared with the conventional bending process.

  As shown in FIG. 6, the flexible printed wiring board 1 is bent at the concave portions 34 and 35 so that the concave portions 34 and 35 are on the outside. The flexible printed wiring board 1 may be bent using a bending jig or by manual bending with a blade or the like pressed against the back side of the recesses 34 and 35. Of course, you may bend the flexible printed wiring board 1 so that the recessed parts 34 and 35 may become inside.

<Method for producing flexible printed wiring board>
The manufacturing method of the flexible printed wiring board 1 includes a step of laminating the cover films 30 and 31 on the substrate 2 so as to cover the conductive patterns 21 and 22 and a step of forming the recesses 34 and 35 in the cover films 30 and 31. .

  The step of laminating the cover films 30 and 31 is performed by sticking the cover films 30 and 31 to the substrate 2. The cover films 30 and 31 are attached by, for example, pressurizing and heating the cover films 30 and 31 on which the adhesive layers 32 and 33 are formed to the substrate 2. The adhesive may be fixed to the cover films 30 and 31 in advance.

  The step of forming the recesses 34 and 35 is preferably performed by irradiating the cover films 30 and 31 with laser light as described above, or by pressing a heated mold against the cover films 30 and 31.

<Advantages>
According to the flexible printed wiring board 1, the flexible printed wiring board 1 can be bent starting from the concave portions 34 and 35. Therefore, the flexible printed wiring board 1 can be easily bent at a target position by using the recesses 34 and 35. Moreover, since the flexible printed wiring board 1 is bent in a state of being partially divided by the concave portions 34 and 35, the bent shape of the flexible printed wiring board 1 can be maintained for a long period of time. Further, since the recesses 34 and 35 can be formed by laser processing, mold formation, or the like, the formation of the recesses 34 and 35 can be performed easily, accurately, and advantageously in terms of cost.

[Second Embodiment]
Next, a flexible printed wiring board according to a second embodiment of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected about the same element etc. as the flexible printed wiring board which concerns on 1st Embodiment, and the duplication description below is abbreviate | omitted.

  The flexible printed wiring board 10 shown in FIGS. 7 to 9 includes a laminate including a flexible substrate 2 and a pair of cover films 30 and 31 laminated on the substrate 2.

  The cover films 30 and 31 are laminated on the surfaces 20a and 20b of the base film 20 so as to cover the conductive patterns 21 and 22 via the adhesive layers 32 and 33.

  The cover film 30 and the adhesive layer 32 have dividing parts 40A and 40B. These dividing portions 40A and 40B are formed over the entire region in the width direction in portions where the conductive patterns 21 and 22 are not formed. Although not clearly shown in the drawing, the cover film 31 and the adhesive layer 33 are also provided with a dividing portion. The notch 40 is formed in a portion of the base film 20 where the conductive pattern 21 is not formed.

  In the base film 20, a part 20Aa of the surface 20a is exposed by the cover film 30 and the dividing portion 40 of the adhesive layer. A recessed portion 41 is formed in the exposed portion 20Aa. The recess 41 corresponds to the recesses 34 and 35 of the flexible printed wiring board 1 according to the first embodiment. Similarly, a part of the surface 20b of the base film 20 is exposed by the dividing portion, and a recessed portion is provided in the exposed portion.

  Also in such a flexible printed wiring board 10, the flexible printed wiring board 10 can be bent using the recess 41.

<Method for producing flexible printed wiring board>
The method for manufacturing the flexible printed wiring board 10 includes a step of laminating the cover films 30 and 31 on the substrate 2 so as to cover the conductive patterns 21 and 22 and a step of forming the recess 41 in the base film 20.

  The process of laminating the cover films 30 and 31 is basically the same as in the case of the first embodiment. However, as the cover films 30 and 31 and the adhesive layer 32, those capable of forming the dividing portions 40A and 40B in the portions corresponding to the regions where the concave portions 41 of the base film 20 are formed are used. Thereby, the cover films 30 and 31 are laminated | stacked on the board | substrate 2 in the state in which a part (part in which the conductive patterns 21 and 22 are not formed) of the base film 20 was exposed.

  The step of forming the recess 41 is the same as that of the first embodiment except that the recess 41 is formed in the base film 20 instead of the cover films 30 and 31.

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

  For example, although the recessed part 41 was exposed in the flexible printed wiring board 10 of FIGS. 7-9, this recessed part may be covered with the cover film.

  Moreover, although the flexible printed wiring board 1 of FIGS. 1-6 and the printed wiring board 10 of FIGS. 7-9 connected between connectors, the said flexible printed wiring board is wiring by which an electronic component is mounted. It can also be applied as a board or a multilayer wiring board.

  Furthermore, the flexible printed wiring board 1 of FIGS. 1-6 and the printed wiring board 10 of FIGS. 7-9 were double-sided wiring boards provided with the board | substrate 2 by which the conductive patterns 21 and 22 were formed in both surfaces of the base film 20. FIG. However, the said flexible printed wiring board can also be comprised as a single-sided wiring board provided with the board | substrate with which the conductive pattern was formed in the single side | surface of a base film.

  Moreover, since the flexible printed wiring board of this invention should just have the recessed part for bending to the target shape, what is necessary is just to determine the number and formation position of a recessed part suitably.

  For example, as shown in FIG. 10, the plurality of dot-like recesses 51 to 55 may be used as the recesses. The plurality of dot-like recesses are arranged in the width direction of the flexible printed wiring board, and the planar view shape of each dot is rectangular (reference numeral 51, 52, 53) or circular (reference numeral 54, 55). It may be a shape. What is necessary is just to design suitably also about the number of dot-shaped recessed parts. According to the dot-shaped recesses 51 to 55 in FIG. 10, the degree of bending of the flexible printed wiring board can be adjusted, and disconnection of the conductive pattern can be prevented. The dot-shaped recess may be formed on the cover film or may be formed on the base film.

  The recesses do not necessarily need to be formed so as to extend in parallel with the width direction of the flexible printed wiring board. For example, the recesses may be formed so as to extend in a direction inclined with respect to the width direction as in the recess 56 shown in FIG. Also good. In such a concave portion 56, not around the width direction but around the direction inclined in the width direction, that is, twisted bending can be realized. Therefore, the inclined concave portion 56 is effective when it is not preferable to bend the flexible printed wiring board around the width direction in terms of the layout of the conductive pattern, and in that case, disconnection of the conductive pattern can be prevented.

  A plurality of recesses (three in the figure) may be formed like the recesses 57, 58, and 59 shown in FIGS. When the plurality of recesses 57 to 59 are formed, the interval (distance between edges) between the adjacent recesses 57 to 59 is preferably 1 mm or less. In such recesses 57 to 59, a bent state having a large curvature radius can be realized. As a result, the load acting on the conductive pattern can be reduced, and disconnection of the conductive pattern can be prevented.

  The cross-sectional shape of the recess may be the form shown in FIGS. 14 to 16.

  The flexible printed wiring board 11 shown in FIG. 14 has a concave portion 60 having a trapezoidal cross section.

  The flexible printed wiring board 12 shown in FIG. 15 has a concave portion 61 having a rectangular cross section.

  The flexible printed wiring board 13 shown in FIG. 16 has a concave portion 62 having a triangular cross section.

  According to these flexible printed wiring boards 11 to 13, the flexible printed wiring boards 11 to 13 can be easily bent into a desired shape using the recesses 60 to 62. Moreover, since the flexible printed wiring boards 11-13 are bent in the state partly parted by the recessed parts 60-62, the bending shape of the flexible printed wiring boards 11-13 can be maintained for a long period of time.

  ADVANTAGE OF THE INVENTION According to this invention, the flexible printed wiring board which can maintain the bending shape of a flexible printed wiring board easily for a long period of time, and can respond suitably to various board | substrate shapes and bending shapes advantageously at a cost is provided.

1,10-13 Flexible printed wiring board 2 Substrate 20 Base film 20a, 20b Surface 20Aa Part (exposed part)
21, 22 Conductive pattern 21a, 22a Individual wiring 30, 31 Cover film 32, 33 Adhesive layer 34, 35, 41, 56-62 Recess 40A, 40B Dividing part 51-55 Dot-shaped recess

Claims (12)

A flexible printed wiring board comprising a laminate having at least one or more substrates including a flexible base film and one or more conductive patterns laminated on one or both sides of the base film. ,
The flexible printed wiring board in which the said laminated body has 1 or several recessed part for bending this laminated body. The laminate further has a cover film covering at least one of the one or more conductive patterns,
The flexible printed wiring board according to claim 1, wherein the recess is formed in the cover film.   The flexible printed wiring board according to claim 2, wherein the cover film contains a liquid crystal polymer as a main component. The laminate further has a cover film covering at least one of the one or more conductive patterns,
The base film is exposed in a portion where the one or more conductive patterns are not formed,
The flexible printed wiring board according to claim 1, wherein the concave portion is formed in an exposed portion of the base film.   The flexible printed wiring board according to claim 4, wherein a depth of the concave portion is 1/5 or more and 3/4 or less with respect to a thickness of the base film.   The flexible printed wiring board according to claim 4, wherein the base film has a liquid crystal polymer as a main component.   The flexible printed wiring board of any one of Claims 1-6 bent so that the said recessed part might become an outer side. Method for forming flexible printed wiring board comprising a laminate having at least one or a plurality of substrates including a flexible base film and one or a plurality of conductive patterns laminated on one or both sides of the base film Because
The manufacturing method of a flexible printed wiring board including the process of forming the 1 or several recessed part for bending the said laminated body.   The method for manufacturing a flexible printed wiring board according to claim 8, wherein the step of forming the recess is performed by irradiating a laser beam.   The method for producing a flexible printed wiring board according to claim 8, wherein the step of forming the recess is performed by pressing a heated mold. Further comprising a step of laminating a cover film on the substrate so as to cover at least one of the one or more conductive patterns.
The method for producing a flexible printed wiring board according to claim 8, wherein the step of forming the concave portion is performed by forming the concave portion in the cover film. The method further includes a step of covering at least one of the one or more conductive patterns and laminating a cover film on the substrate so that a portion where the conductive pattern is not formed is exposed.
The method for producing a flexible printed wiring board according to any one of claims 8 to 11, wherein the step of forming the recess is performed by forming the recess in the base film.

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