JP2018010967A - Flexible printed wiring board and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a long strip flexible printed wiring board having a shape curved in the transverse direction inexpensively and stably.SOLUTION: In a strip flexible printed wiring board including a first and second substrate members having a base layer composed of thermoplastic resin, a wiring layer including a conductor formed on the base layer, and a cover layer formed on the wiring layer and composed of thermoplastic resin, and curved in the transverse direction, and a junction between the longitudinal ends of the first and second substrate members adjoining in the longitudinal direction, at the junction, facing conductors of the wiring layer of the first and second substrate members are joined conductively, facing base layers of the first and second substrate members, a base layer of the first substrate member and a cover layer of the second substrate member facing thereto, or a cover layer of the first substrate member and a base layer of the second substrate member facing thereto, are joined.SELECTED DRAWING: Figure 1

Description

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

  2. Description of the Related Art Conventionally, various wirings are used for electrical connection between components provided in various electronic devices such as communication and video devices, industrial devices, robots, game machines and the like. In particular, for example, a cable bear (registered trademark) is used in a portion where smooth movement of components in the device is required (see Patent Document 1). In this technique, since a member for supporting the cable is necessary, a relatively large space is required for the arrangement space of the cable bear. On the other hand, the arrangement space can be narrowed by using a belt-like flexible printed wiring board. When a general flexible printed wiring board is used in the air in the form of a belt, it may be in a sagging state. Therefore, damage may occur due to contact between surrounding components and the flexible printed wiring board. On the other hand, a technique is known in which a belt-like flexible printed wiring board is formed in a state of being bent in the short direction so that it does not sag even when used in the air (see Patent Document 2). . The strip-shaped flexible printed wiring board curved in the short direction can stand on its own without sagging even when bent in one position in the longitudinal direction. In such a flexible printed wiring board, one end of the longitudinal direction is fixed to one of the two members, and the other end of the longitudinal direction is fixed to the other of the two members, and the two members are parallel to the longitudinal direction. Even in the case of relative movement in the virtual plane, the position in the longitudinal direction of the bent portion moves while following the relative movement while remaining independent (see Patent Document 4).

  As a method of forming the flexible printed wiring board so as to bend in the short side direction, there is a method of utilizing a warp due to elasticity generated in the coverlay film when the coverlay film is bonded to the base film by heating and pressing. For example, a method of using materials having different heat shrinkage rates for the coverlay film and the base film and a method of devising the thickness of the adhesive are known (see Patent Document 2). However, in these methods, the thickness, arrangement, and material of each material may be limited. In addition, since the intermediate product is curved in the initial stage of the manufacturing process, a device for processing the intermediate product of a general flat flexible printed wiring board may be difficult or unusable. . Therefore, post-processes such as plating and shape processing may be difficult. On the other hand, a technique is known in which a thermoplastic resin is used as a material for the coverlay film and the base film of a flexible printed wiring board, and thermoforming is performed at a later stage of the manufacturing process of the flexible printed wiring board (Patent Document 3). See). In this technology, a liquid crystal polymer (LCP: Liquid Crystal Polymer) that can be stretched as a thermoplastic resin is used, and is thermoformed at a temperature that is several tens to 100 ° C. lower than the softening temperature of the resin for about 30 to 60 minutes. . Using this technique, a strip-shaped flexible printed wiring board curved in the short direction can be produced.

FIG. 8 is a diagram for explaining a conventional technique for producing a strip-shaped flexible printed wiring board curved in a short direction using LCP as an insulating resin constituting a base film or a coverlay film. First, as shown in FIG. 8A, a single-sided copper-clad laminate 23 having a copper foil layer 22 (a 12 μm thick copper foil) on one side of an insulating resin 21 (a 50 μm thick LCP film) is prepared, The wiring pattern 22b is formed by etching using a photofabrication technique. Further, a cover lay 24 made of a 50 μm thick LCP film 24a and an adhesive 24b in which openings such as terminals are previously formed is prepared. The cover lay 24 is laminated on the surface on which the wiring pattern is formed, and the curing reaction of the adhesive 24b is completed by heating and curing in an oven, whereby a planar laminated base material 25 as shown in FIG. 8B is obtained. . The size is, for example, 500 mm in the longitudinal direction and 30 mm in the short direction, as shown in the top view of FIG.

  The laminated base material 25 is heated in an oven or the like in a state where it is sandwiched by a jig having a curved surface curved with a curvature R in the short direction (for example, a shape in which a pipe is cut in half in the longitudinal direction). As shown by the arrow 27 in B), the flexible printed wiring board 26 shown in FIG. 9 is obtained by forming into a shape curved with a curvature R in the lateral direction. In this example, a curved shape having a convex curvature R in the direction of the insulating resin 21 is formed.

  FIG. 9 is a perspective view showing a state when the flexible printed wiring board 26 after use is used. The curvature R is, for example, 15 mm. When the molded flexible printed wiring board 26 is bent in the longitudinal direction in the vicinity of the center in the longitudinal direction, the flexible printed wiring board 26 is U-shaped in the longitudinal direction at the bent position as shown in FIG. become. In this state, as shown in FIGS. 10B and 10C, the flexible printed wiring board 26 does not hang down by itself, and the bent portion can freely move in the longitudinal direction. As a result, the flexible printed wiring board follows the longitudinal movement of the both ends in the longitudinal direction as indicated by the arrows 28a and 28b in the virtual plane parallel to the longitudinal direction, and the bent shape and the short side in the longitudinal direction follow. Deforms while maintaining the curved shape of the direction and being self-supporting.

JP 2008-243839 A JP2013-74166A JP 2011-134484 A Japanese Utility Model Publication No. 63-194212

JPCA Show 2014

  As described above, in the method of manufacturing a flexible printed wiring board having a curved shape in the short direction by heating and forming a thermoplastic resin with a jig curved in the short direction, the flexible printed wiring to be manufactured The length of the plate is limited by the length of the forming jig and the size of the heating oven. In order to produce a long strip-shaped flexible printed wiring board curved in the short direction, first, a large-sized oven capable of producing a long strip-shaped flexible printed wiring board using LCP or the like and heating it using a long molding jig Etc. are required. Therefore, it has been difficult to inexpensively produce a long strip-shaped flexible printed wiring board (for example, metric order) having a shape curved in the short direction. Further, when the length of the flexible printed wiring board is increased, there is a problem that the wiring length is increased and the yield is lowered.

  The present invention has been made in view of this point, and an object of the present invention is to stably and inexpensively produce a long strip-shaped flexible printed wiring board having a shape curved in the short-side direction.

The present invention for solving the above problems includes a base layer made of a thermoplastic resin, a wiring layer including a conductor portion formed on the base layer, and a thermoplastic resin formed on the wiring layer. A first substrate member and a second substrate member curved in the lateral direction,
A junction between the longitudinal ends of the first substrate member and the second substrate member adjacent in the longitudinal direction;
A strip-shaped flexible printed wiring board having
In the joint,
The conductor portion of the wiring layer of the first substrate member and the conductor portion of the wiring layer of the second substrate member facing it are joined so as to be conductive, and
The base layer of the first substrate member and the base layer of the second substrate member opposite thereto, or
A base layer of the first substrate member and a cover layer of the second substrate member facing the base layer; or
A flexible printed wiring board, wherein a cover layer of the first board member and a base layer of the second board member facing the first board member are bonded to each other.

  Here, “facing” means facing in the direction perpendicular to the curved surface of the substrate member. This flexible printed wiring board has a configuration in which a plurality of board members shorter than the entire length are joined at a joining portion. Since the board | substrate members are joined so that the conductor parts which a wiring layer opposes in a junction part can electrically conduct, it functions as one flexible printed wiring board as a whole. In addition, since the base layers facing each other or the base layer and the cover layer facing each other are joined at the joint portion, the substrate member is not separated at the joint portion, so that the flexible printed wiring board can be flexible as a whole. Following the relative movement of the two members fixed to both ends of the flexible printed wiring board in a state bent in the longitudinal direction of the printed wiring board, while maintaining the bending shape in the longitudinal direction and the bending shape in the short direction, A motion in which the bent portion moves in the longitudinal direction can be performed. From these facts, the flexible printed wiring board of the present invention is composed of a plurality of short board members and a joint provided between adjacent board members, but is equivalent to a long flexible printed wiring board formed integrally. Flexibility and followability of the bent portion accompanying relative movement of both ends.

The present invention includes a method for manufacturing a flexible printed wiring board configured as described above.
That is, the present invention includes a base layer made of a thermoplastic resin, a wiring layer including a conductor portion formed on the base layer, a cover layer made of a thermoplastic resin formed on the wiring layer, Laminating layers to produce a first substrate member and a second substrate member;
A shape processing step of bending each of the first substrate member and the second substrate member in a lateral direction;
A joining step of joining the end portions in the longitudinal direction of the first substrate member and the second substrate member processed in the shape adjacent to each other in the longitudinal direction using a joining member;
Have
The joining member is
Joining the conductor portion of the wiring layer of the first substrate member and the conductor portion of the wiring layer of the second substrate member facing the conductor portion so as to be conductive; and
The base layer of the first substrate member and the base layer of the second substrate member opposite thereto, or
A base layer of the first substrate member and a cover layer of the second substrate member facing the base layer; or
A method for manufacturing a strip-shaped flexible printed wiring board, comprising joining a cover layer of the first substrate member and a base layer of the second substrate member facing the cover layer.

According to this manufacturing method, a long strip-shaped flexible print having a shape curved in the short direction as a whole is obtained by first applying a shape process to bend in a short direction on a short substrate member and bonding it with a bonding member. A wiring board can be manufactured. Therefore, it is sufficient for the forming jig required for the shape processing to bend in the short direction, as long as it has a size sufficient to shape the short substrate member, and a long strip-shaped flexible printed wiring curved in the short direction. A board can be manufactured at low cost. Further, the length of the final flexible printed wiring board can be easily adjusted by the number of substrate members to be joined, and is not restricted by the size of the molding jig as in the prior art. Furthermore, even when the final flexible printed wiring board is long, the wiring length of each board member can be short, so that a decrease in yield can be suppressed.

In the flexible printed wiring board of the present invention, when the base layer of the first board member and the base layer of the second board member facing it are joined at the joint,
The shape of the first substrate member in the short direction is convex in the direction of the base layer and the shape of the second substrate member in the short direction is convex in the direction of the cover layer, or
The curved shape in the short direction of the first substrate member is a convex shape in the direction of the cover layer, and the curved shape in the short direction of the second substrate member is a convex shape in the direction of the base layer. Also good.

  The flexible printed wiring board having this configuration has two types: a first substrate member curved in a convex shape in the direction of the base layer, and a second substrate member curved in a convex shape in the direction of the cover layer. These substrate members are prepared in a shape processing step, and the first substrate member and the second substrate member are arranged in the longitudinal direction so as to have a curved shape, and are joined by a joining member. Therefore, in the joint portion, the conductor portions facing each other in the wiring portion are joined to each other, and the opposing portions of one base layer and the other base layer of the adjacent substrate members are joined.

The flexible printed wiring board of the present invention includes a base layer of the first board member and a cover layer of the second board member facing the base layer of the first board member, or a cover layer of the first board member and the same at the joint. In the case where the base layers of the second substrate members facing each other are bonded,
Both the first substrate member and the second substrate member are curved in the short direction, either convex in the direction of the base layer, or both convex in the direction of the cover layer. Also good.

  The flexible printed wiring board having this configuration is formed by processing either a substrate member curved in a convex shape toward the base layer or a substrate member curved in a convex shape toward the cover layer. It can be manufactured by preparing it in the process, arranging it in the longitudinal direction so that the curved shape matches, and joining with a joining member. Therefore, in the joint portion, the conductor portions facing each other in the wiring portion are joined to each other, and a portion where one base layer and the other cover layer of adjacent substrate members face each other, or one cover layer and the other base. A portion facing the layer is joined.

  Since the flexible printed wiring board of the present invention is composed of a plurality of board members, the specifications of the first board member and the second board member may be made common or different as appropriate depending on the application and purpose. Can do. For example, the first substrate member and the second substrate member can be configured such that the thickness and physical properties of the thermoplastic resin are common. On the other hand, the first substrate member and the second substrate member may be configured such that at least one of the thickness and physical properties of the thermoplastic resin is different.

  In the flexible printed wiring board of the present invention, an anisotropic conductive material is preferably used for the joint. Thereby, while facing the conductor portions of the wiring layer at the joint portion, the facing base layers or the facing base layer and the cover layer can be mechanically joined. When manufacturing the flexible printed wiring board of the structure which used the anisotropic conductive material for the junction part, an anisotropic conductive film and anisotropic conductive paste can be used as a joining member. In addition, a liquid crystal polymer can be used as the thermoplastic resin.

In the method for manufacturing a flexible printed wiring board according to the present invention, the shape processing step uses the jig having a curved surface having substantially the same shape as the curved shape in the lateral direction, and the second substrate member and the second substrate member. Including a step of thermoforming the substrate member,
The joining step may include a step of thermocompression bonding the end portions of the first substrate member and the second substrate member and the joining member at a temperature lower than the heating temperature of the shape processing step. .

  In the joining process after the shape processing, since the thermocompression bonding is performed at a temperature lower than the heating temperature in the shape processing process, the shape after the processing can be maintained in the joining process.

In the method for manufacturing a flexible printed wiring board according to the present invention, the shape processing step uses the jig having a curved surface having substantially the same shape as the curved shape in the lateral direction, and the second substrate member and the second substrate member. Including a step of thermoforming the substrate member,
In the bonding step, the first substrate member, the end portions of the second substrate member, and the bonding member are thermocompression bonded using a jig having a curved surface that is substantially the same shape as the curved shape in the lateral direction. Steps may be included.

  In the joining process after shape processing, thermocompression bonding is performed in a state where the shape after processing is maintained, so that the shape after processing can be maintained even when thermocompression bonding is performed at a temperature equal to or higher than the heating temperature of the shape processing process. it can.

  In addition, this invention can be comprised combining said each structure as much as possible.

  ADVANTAGE OF THE INVENTION According to this invention, the long strip | belt-shaped flexible printed wiring board which has the shape curved in the transversal direction can be produced stably cheaply.

FIG. 1 is an explanatory diagram of a manufacturing process of a flexible printed wiring board according to Embodiment 1 of the present invention. FIG. 2 is an explanatory diagram of the manufacturing process of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 3 is an explanatory diagram of the manufacturing process of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 4 is an explanatory diagram of the manufacturing process of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 5 is an explanatory diagram of the manufacturing process of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 6 is a perspective view showing a state in use of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 7 is an explanatory diagram of the manufacturing process of the flexible printed wiring board according to the first embodiment of the present invention. FIG. 8 is an explanatory diagram of a manufacturing process of a conventional flexible printed wiring board. FIG. 9 is an explanatory diagram of a manufacturing process of a conventional flexible printed wiring board. FIG. 10 is a perspective view showing a state when a conventional flexible printed wiring board is used.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified.

<Method for producing flexible printed wiring board>
FIG. 1 is an explanatory diagram of a manufacturing process of a flexible printed wiring board according to Embodiment 1 of the present invention. First, as shown in FIG. 1 (A), a single-sided copper-clad laminate 3 having a copper foil layer 2 (a 12 μm thick copper foil) on one side of an insulating resin 1 (a 50 μm thick LCP film) as a base layer. And a wiring pattern 2b as a conductor portion is formed by etching by a photofabrication method to form a wiring layer. Further, a cover lay 4 is prepared as a cover layer made up of a 50 μm thick LCP film 4a in which openings such as terminals are formed in advance and a 15 μm thick adhesive 4b. It is preferable to use a low-elastic material for the adhesive 4b because the influence on the subsequent molding process can be suppressed. Specifically, since the elastic coefficient of the LCP film is about 3 to 4 GPa, the influence on the moldability can be suppressed by using an adhesive having an elastic coefficient of 2 GPa or less, which is less than half of this. Moreover, since it heats for about 30 minutes at the temperature of about 200 degreeC at the time of shaping | molding, what does not deteriorate adhesiveness and an electrical insulation characteristic remarkably with this heat history is suitable.

  Next, as shown in FIG. 1B, the coverlay 4 is laminated on the surface on which the wiring pattern is formed, and the curing reaction of the adhesive is completed by curing in an oven at 150 to 200 ° C. for about 1 to 2 hours. To obtain a laminated substrate 5 on a plane. As shown in the top view of FIG. 1C, the planar size of the laminated base material 5 is 500 mm in the longitudinal direction and 30 mm in the lateral direction.

  Next, shape processing is performed on the laminated base material 5 to produce a substrate member. In Example 1, as shown in FIG. 2A, two types of substrate members A and B having different short-side bending directions are produced. The substrate member A has a curved surface in the short direction that is convex in the direction of the insulating resin 1, and the substrate member B is convex in the direction of the cover lay 4. In order to produce these substrate members A and B, the laminated base material 5 is sandwiched between molding jigs having a curved surface curved with a curvature R in the lateral direction (for example, a shape in which a pipe is cut in half in the longitudinal direction). Heat in an oven. Thereby, the laminated base material 5 made of LCP material is deformed into a shape curved with a curvature R in the lateral direction. Since it is difficult to heat-mold those having a total length exceeding 100 cm due to restrictions on the internal dimensions of an oven or the like, the molding was performed by heating at 200 ° C. for 30 minutes using a jig having a length of 50 cm. In Example 1, since LCP was used as the thermoplastic resin, the heating temperature at the time of molding was set to 200 ° C. based on the softening temperature. However, when other materials are used as the thermoplastic resin, Based on the softening temperature of the plastic resin, the heating temperature in the molding process is set. As shown in FIG. 2 (A), the substrate member A shown in the perspective view of FIG. 2 (C) is obtained by performing shape processing for bending the laminated substrate 5 in the short direction so that the insulating resin 1 becomes convex. obtain. On the other hand, as shown in FIG. 2 (B), the substrate member shown in the perspective view of FIG. 2 (D) is obtained by performing shape processing for bending the laminated substrate 5 in the short direction so that the cover lay 4 side is convex. B is obtained. The curvature R of the short direction curvature was 15 mm.

  Next, as shown in FIG. 3A, the directions of the convex shapes of the substrate members A and B are aligned. In the perspective view of FIG. 3A, the cover member 4 is the upper surface and the insulating resin 1 is the lower surface for the substrate member A, and the insulating resin 1 is the upper surface and the cover lay 4 is the lower surface for the substrate member B. Thus, the substrate members A and B are adjacent to each other at the end portions 9 and 10 in the longitudinal direction.

  As shown in FIGS. 3B, 3C, and 3D, the longitudinal end of the substrate member is formed so that the terminal portion 2c of the wiring pattern 2b of the wiring layer is exposed. Yes. Both the board members A and B are formed such that the length in the longitudinal direction of the cover lay 4 is shorter than the length in the longitudinal direction of the wiring pattern 2b and the insulating resin 1 at the end in the longitudinal direction.

Next, as shown in FIG. 4A, the substrate members A and B are overlapped so that the portion 2c where the wiring pattern 2b of the substrate members A and B is exposed faces the direction perpendicular to the plane of the substrate member. ACF6 (Anisotropic Conductive Film) having a thickness of 35 μm as a joining member so as to be sandwiched between the opposing ends 2c of the wiring patterns 2b of the board members A and B.
Dexerials DP3342MS) is placed and joined by thermocompression bonding of ACF6. Thereby, a joined portion as shown in FIG. 4B is obtained.
Further, as shown in FIG. 4C, at locations where the wiring patterns 2b of the board members A and B do not exist, the ACF 6 as a bonding member between the insulating resins 1 facing each other in the direction perpendicular to the plane of the board member. And are joined by thermocompression bonding. Thereby, a joined portion as shown in FIG. 4D is obtained.
In this way, the opposing conductor portions of the wiring layers are joined to each other at the longitudinal ends of the board members A and B, and the opposing base layers are joined together, so that a long strip-shaped flexible printed wiring board is obtained. It is done.
As shown in FIG. 4B, the longitudinal end surface 17 of the cover lay 4 of the substrate member A and the longitudinal end surface 16 of the insulating resin 1 of the substrate member B are adjacent (contacted). Alternatively, they may be separated as shown in FIG. The end faces in the longitudinal direction may be adjacent (contacted) as shown in FIG. 4B at both the place where the opposing conductor portions are joined and the place where the opposing base layers are joined, Both may be separated as shown in FIG. Moreover, when adjoining (contacting), the end surfaces of a longitudinal direction may be joined by ACF, and may not be joined. Even when the end faces in the longitudinal direction are not joined by ACF, the opposing base layers and conductor portions are joined by ACF, which is sufficient for joining the substrate members.

  In Example 1, the thermocompression bonding conditions of the ACF in the joining process were first temporarily attached at 50 ° C., 1.5 MPa, and 1 sec, and then finally crimped at 130 ° C., 2 MPa, and 10 sec. Thus, since the joining temperature is lower than the molding temperature and is a short time, the curved shape of the curvature R in the short direction of the substrate members A and B is maintained even after the joining process. In Example 1, the heating temperature in the joining process was set to 130 ° C., because the ACF was used as a joining member. When using another material as the joining member, the heating temperature in the joining process is a temperature equal to or higher than the softening temperature of the joining member and lower than the softening temperature of the thermoplastic resin (LCP in Example 1). Set it. This is to prevent the curved shape of the substrate member from being relaxed in the bonding step. The length in the longitudinal direction of the terminal portion 2c facing the board members A and B in the joint portion 11 was 2 mm. The ACF is not limited to the above example as long as it has a characteristic capable of being thermocompression-bonded in a temperature range in which a curved shape (molded shape) in the short direction can be maintained. Moreover, it is also possible to use ACP (Anisotropic Conductive Paste) as a joining member. In order to suppress the thickness of the overlapping portion of the terminal portion 2c of the joint portion, the copper foil thickness may be reduced by soft etching or the like in the terminal portion 2c. Further, for the surface treatment of the terminal portion 2c, a water-soluble preflux suitable for bonding by ACF, gold plating, or the like may be used.

  If thermocompression bonding in the joining process between the end portions of the substrate member is performed at a temperature comparable to or higher than the heating temperature in the molding process (in Example 1, for example, a temperature around 200 ° C.), the molded shape may not be maintained. . When it is desired to perform thermocompression bonding in the joining process under such temperature conditions, as shown in FIG. 5A, crimping jigs 13a and 13b having curved surfaces curved in the short direction having the same shape as the molded shape. As shown in FIG. 5 (B), it is preferable to perform the thermocompression bonding in the joining process in a state where the joining portions of the substrate members A and B are sandwiched between the crimping portions 13a and 13b. By doing so, the curved shape in the short direction of the substrate members A and B in the vicinity of the joint is maintained even after the joining process.

<Configuration of flexible printed wiring board>
The flexible printed wiring board manufactured by the above manufacturing process will be described.
As shown in FIG. 5C, the flexible printed wiring board 7 has a joining portion 11 between the end portions in the longitudinal direction of the adjacent board members A and B, and has a long shape curved in the lateral direction. It is a strip-shaped flexible printed wiring board.

As shown in FIG. 1A, FIG. 1B, FIG. 4B, and FIG. 4D, each of the substrate members A and B is a base layer (insulating resin 1) made of a thermoplastic resin (LCP). And a wiring layer including a conductor portion (wiring pattern 2b) formed on the base layer, and a cover layer (cover lay 4) made of thermoplastic resin (LCP) formed on the wiring layer. The shape is curved in the short direction. In the joint portion 11 between the longitudinal ends of the substrate members A and B adjacent in the longitudinal direction, the conductor portion (terminal portion 2c) of the wiring layer of the substrate member A (first substrate member) and the substrate opposed thereto. The conductive portion (terminal portion 2c) of the wiring layer of the member B (second substrate member) is joined to be conductive, and the insulating resin 1 (base layer) of the substrate member A (first substrate member) and the same The insulating resin 1 (base layer) of the opposing substrate member B (second substrate member) is bonded.

  In the flexible printed wiring board 7 according to the first embodiment, the curved shape in the short direction of the substrate member A (first substrate member) among the adjacent substrate members A and B protrudes in the direction of the insulating resin 1 (base layer). The curved shape in the short direction of the substrate member B (second substrate member) is a convex shape in the direction of the cover lay 4 (cover layer). Of the adjacent substrate members A and B, the substrate member A (first substrate member) has a curved shape in the short direction that is convex toward the cover lay 4 (cover layer), and the substrate member B ( The shape of the second substrate member) in the short direction may be a convex shape in the direction of the insulating resin 1 (base layer).

<The excellent point of the flexible printed wiring board of Example 1>
The function of the flexible printed wiring board 7 was verified. First, as shown by the arrow 12 in FIG. 5C, the vicinity of the center in the longitudinal direction of the flexible printed wiring board 7 is bent in the direction in which the convex shape of the short direction is directed outward, as shown in FIG. ), The flexible printed wiring board 7 is U-shaped in the longitudinal direction at the bent position. The curvature R of the bent portion is substantially the same as the curvature R of the curved shape in the short direction of the flexible printed wiring board 7 (here, R = 15 mm). In this state, the flexible printed wiring board 7 does not hang down by itself as shown in FIG. With respect to the flexible printed wiring board 7, as shown in FIG. 6B, both end portions 14a and 14b are linearly indicated by arrows 15a and 15b in a virtual plane parallel to the longitudinal direction of the flexible printed wiring board 7. When the relative movement is performed, the bending movement is possible so that the position of the bending portion smoothly moves in the longitudinal direction following the relative movement while maintaining the bending shape in the longitudinal direction and the curved shape in the short direction. . Even when the joint portion 11 is a bent portion, there was no particular resistance to the bending motion accompanying the relative movement. Even after 10 million repetitive linear relative movement tests, the DC resistance change of the wiring layer was 3% or less, and no abnormality such as deformation of the base material or peeling of the joint 11 was observed. Therefore, according to Example 1, the long flexible printed wiring board 7 which was curving in the transversal direction with a total length of 1000 mm (1 m) could be produced using a forming jig having a length of 500 mm.

(Other)
In Example 1, the curved shape in the short direction of one substrate member A of adjacent substrate members A and B is a convex shape in the direction of the base layer (insulating resin 1), and the short shape of the other substrate member B is short. Although the flexible printed wiring board 7 having a configuration in which the curved shape in the hand direction is convex in the direction of the cover layer (cover lay 4) and the manufacturing method thereof have been described, the present invention is not limited to this. In the flexible printed wiring board of the present invention, the curved shape in the short direction of adjacent substrate members is either a convex shape in the direction of the base layer (insulating resin 1), or both cover layers (coverlay 4). ) May be convex. For example, in the case of using only a substrate member having a convex shape in the short direction, as shown in FIG. 2C, in the direction of the base layer (insulating resin 1), FIG. ), The length of the cover lay 4 in the longitudinal direction is shorter than that of the wiring pattern 2b and the insulating resin 1, and the length of the insulating resin 1 in the longitudinal direction of the wiring pattern 2b and the cover lay 4 is longer. The short-shaped substrate member D is prepared, and the end portions in the longitudinal direction thereof are joined to each other in the same manner as in the first embodiment, so that the curved shape in the short-side direction of the adjacent substrate members is the base. A flexible printed wiring board having a convex shape in the direction of the layer (insulating resin 1) is obtained. In the flexible printed wiring board having this configuration, the opposing conductor portions (wiring patterns 2b) of the wiring layers of the adjacent board members C and D are joined to each other, and the base layer (insulating resin 1) of one of the board members C and The cover layer (cover 4) of the other substrate member D facing it is joined. In addition, when a long strip-shaped flexible printed wiring board is manufactured using only a substrate member having a convex shape in the direction of the cover layer (cover lay 4), the conductor portion ( The wiring patterns 2b) are joined to each other, and the cover layer (cover lay 4) of one substrate member C and the base layer (insulating resin 1) of the other substrate member D facing the same are joined.

  In the first embodiment, an example in which two substrate members are joined is shown. However, by joining three or more substrate members, a strip-shaped flexible printed wiring board curved in a longer lateral direction can be created. The flexible printed wiring board manufactured by the method of the present invention by joining three or more substrate members has a plurality of joint portions. The configuration of each joint portion is the same as that of the substrate members A and B described in the first embodiment. It is good also as a structure of a junction part, and it is good also as a structure of the junction part of the board | substrate members C and D mentioned above. Further, the configuration of the plurality of joint portions may be the same or different. When joining three or more board members, there is no need to increase the size of heating tools such as molding jigs and ovens. No restrictions on the size of jigs and ovens. Therefore, it is also possible to produce a strip-shaped flexible printed wiring board curved in the short direction of several meters. Since the strip-shaped flexible printed wiring board curved in the short direction of Example 1 is manufactured by combining short substrate members, it suppresses a decrease in yield as compared with the case of manufacturing a long flexible printed wiring board by integral molding. There is also an advantage of being able to do it.

  In the first embodiment, the plurality of board members A and B constituting the flexible printed wiring board 7 have the same thickness and physical properties of the thermoplastic resin, but the present invention is not limited to this. The specifications of the plurality of substrate members may be varied depending on the application and purpose. For example, among the plurality of board members constituting the flexible printed wiring board 7, the board member located at the end is fixed to two members that move relative to each other in the actual use state. In order to secure the fixing strength, only the substrate members located at both ends may be made thicker in the thickness of the thermoplastic resin, or a material having a high softening temperature may be used when close to a high temperature heat source.

  In Example 1, although the example which uses a liquid crystal polymer (LCP) as an insulating resin was shown, if it is a material which has insulation, flexibility, and thermoplasticity, it will not be limited to this. Moreover, although the example which uses ACF and ACP as a joining member was demonstrated, if it is a material which has electroconductivity and adhesiveness, it will not be limited to this.

DESCRIPTION OF SYMBOLS 1 Insulation resin 2 Copper foil 2b Wiring pattern 3 Single-sided copper clad laminated board 4 Coverlay 4a LCP film 4b Adhesive material 5 Laminate base material 6 ACF
7 Flexible printed wiring board 8a having a long overall length that can be slid / slidable Curved direction 8b of substrate member A Curved direction of substrate member 9 End 10 where substrate member A is bonded End 11 where substrate member B is bonded Bending direction 13a, 13b during use of part 12 Ends 15a, 15b of flexible printed wiring board Relative moving direction 16 End face 17 End face 21 Insulating resin 22 Copper foil 22b Wiring pattern 23 Single-sided copper-clad laminate 24 Cover Lay 24a LCP film 24b Adhesive 25 Laminate base material 26 Self-supporting / slidable flexible printed wiring board 27 Curvature direction of flexible printed wiring board

As described above, in the method for producing a flexible printed wiring board having a curved shape in the short direction by thermoforming a thermoplastic resin by sandwiching it with a jig having a curved shape in the short direction, the flexible printed wiring to be produced The length of the plate is limited by the length of the forming jig and the size of the heating oven. In order to produce a long strip-shaped flexible printed wiring board curved in the short direction, first, a large-sized oven capable of producing a long strip-shaped flexible printed wiring board using LCP or the like and heating it using a long molding jig Etc. are required. Therefore, it has been difficult to inexpensively produce a long strip-shaped flexible printed wiring board (for example, metric order) having a shape curved in the short direction. Further, when the length of the flexible printed wiring board is increased, there is a problem that the wiring length is increased and the yield is lowered.

If thermocompression bonding in the joining process between the end portions of the substrate member is performed at a temperature comparable to or higher than the heating temperature in the molding process (in Example 1, for example, a temperature around 200 ° C.), the molded shape may not be maintained. . When it is desired to perform thermocompression bonding in the joining process under such temperature conditions, as shown in FIG. 5A, crimping jigs 13a and 13b having curved surfaces curved in the short direction having the same shape as the molded shape. As shown in FIG. 5 (B), it is preferable to perform the thermocompression bonding in the joining process in a state where the joining portions of the substrate members A and B are sandwiched between the crimping jigs 13a and 13b. By doing so, the curved shape in the short direction of the substrate members A and B in the vicinity of the joint is maintained even after the joining process.

In the first embodiment, the plurality of board members A and B constituting the flexible printed wiring board 7 have the same thickness and physical properties of the thermoplastic resin, but the present invention is not limited to this. The specifications of the plurality of substrate members may be varied depending on the application and purpose. For example, among the plurality of board members constituting the flexible printed wiring board 7, the board member located at the end is fixed to two members that move relative to each other in the actual use state. To ensure strength of the fixed, only the substrate member positioned at both ends, the thickness of the thermoplastic resin thickness Kushitari may or using a material softening temperature is higher physical properties in the case of close proximity to the high-temperature heat source.

Claims (13)

A base layer made of a thermoplastic resin, a wiring layer including a conductor formed on the base layer, and a cover layer made of a thermoplastic resin formed on the wiring layer. A first substrate member and a second substrate member curved in a direction;
A junction between the longitudinal ends of the first substrate member and the second substrate member adjacent in the longitudinal direction;
A strip-shaped flexible printed wiring board having
In the joint,
The conductor portion of the wiring layer of the first substrate member and the conductor portion of the wiring layer of the second substrate member facing it are joined so as to be conductive, and
The base layer of the first substrate member and the base layer of the second substrate member opposite thereto, or
A base layer of the first substrate member and a cover layer of the second substrate member facing the base layer; or
A flexible printed wiring board, wherein a cover layer of the first board member and a base layer of the second board member facing the first board member are joined. In the bonding portion, when the base layer of the first substrate member and the base layer of the second substrate member facing the first substrate member are bonded,
The shape of the first substrate member in the short direction is convex in the direction of the base layer and the shape of the second substrate member in the short direction is convex in the direction of the cover layer, or
The shape of the first substrate member in the short direction is convex in the direction of the cover layer, and the shape of the second substrate member in the short direction is convex in the direction of the base layer. Item 8. The flexible printed wiring board according to Item 1. In the joint portion, the base layer of the first substrate member and the cover layer of the second substrate member facing it, or the cover layer of the first substrate member and the second substrate member facing it. When the base layer is joined,
Both of the first substrate member and the second substrate member are curved in the short direction in a convex shape in the direction of the base layer, or both are convex in the direction of the cover layer. Item 8. The flexible printed wiring board according to Item 1.   The flexible printed wiring board according to claim 1, wherein the first board member and the second board member have the same thickness and physical properties of a thermoplastic resin.   The flexible printed wiring board according to any one of claims 1 to 3, wherein the first board member and the second board member are different in at least one of a thickness and a physical property of a thermoplastic resin.   The flexible printed wiring board according to claim 1, wherein the joint portion is made of an anisotropic conductive material.   The flexible printed wiring board according to claim 1, wherein the thermoplastic resin is made of a liquid crystal polymer. A first layer is formed by laminating a base layer made of a thermoplastic resin, a wiring layer including a conductor portion formed on the base layer, and a cover layer made of a thermoplastic resin formed on the wiring layer. Producing a substrate member and a second substrate member;
A shape processing step of bending each of the first substrate member and the second substrate member in a lateral direction;
A joining step of joining the end portions in the longitudinal direction of the first substrate member and the second substrate member processed in the shape adjacent to each other in the longitudinal direction using a joining member;
Have
The joining member is
Joining the conductor portion of the wiring layer of the first substrate member and the conductor portion of the wiring layer of the second substrate member facing the conductor portion so as to be conductive; and
The base layer of the first substrate member and the base layer of the second substrate member opposite thereto, or
A base layer of the first substrate member and a cover layer of the second substrate member facing the base layer; or
A method for manufacturing a strip-shaped flexible printed wiring board, comprising joining a cover layer of the first substrate member and a base layer of the second substrate member facing the cover layer.   The method for manufacturing a flexible printed wiring board according to claim 8, wherein the joining member is an anisotropic conductive film.   The method for manufacturing a flexible printed wiring board according to claim 8, wherein the joining member is an anisotropic conductive paste. The shape processing step includes a step of thermoforming the first substrate member and the second substrate member using a jig having a curved surface that is substantially the same shape as the curved shape in the lateral direction,
The said joining process includes the process of thermocompression-bonding the edge part of the said 1st board | substrate member and the said 2nd board | substrate member, and the said joining member at the temperature lower than the heating temperature of the said shape processing process. The manufacturing method of the flexible printed wiring board of any one of Claims 1. The shape processing step includes a step of thermoforming the first substrate member and the second substrate member using a jig having a curved surface that is substantially the same shape as the curved shape in the lateral direction,
In the bonding step, the first substrate member, the end portions of the second substrate member, and the bonding member are thermocompression bonded using a jig having a curved surface that is substantially the same shape as the curved shape in the lateral direction. The manufacturing method of the flexible printed wiring board of any one of Claims 8-10 including a process.   The method for manufacturing a flexible printed wiring board according to claim 8, wherein the thermoplastic resin is made of a liquid crystal polymer.

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