JP2017135216A - Flexible printed board, and method for manufacturing flexible printed board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide: a flexible printed board which can be prevented from sticking to a hot platen having a flat and smooth face; and a method for manufacturing the flexible printed board.SOLUTION: A flexible printed board 10A comprises: a first insulator layer 21 formed by using, as a material, a liquid crystal polymer which is a thermoplastic resin; a wiring layer 22 formed on a surface of the first insulator layer 21 and including a plurality of wiring lines 221; a second insulator layer 32 disposed so as to cover the wiring layer 22 on the side opposite to the first insulator layer 21, and formed from a thermoplastic resin; a first adhesive layer 31 interposed between the wiring layer 22 and the second insulator layer 32 to bond the layers, filling in between the plurality of wiring lines 221, and covering the wiring layer 22; and a first rough surface part 211 provided on a face of the first insulator layer 21 on the side opposite to the wiring layer 22, and having a roughness of which the ten-point average roughness Rz is within a range of 1-5 μm.SELECTED DRAWING: Figure 1

Description

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

  In recent years, the development of robots has been remarkable, such as the appearance of robots with various movements. In addition, wearable electronic devices that can be worn on the human body and clothes have been developed and put into practical use with various devices. These robots and wearable electronic devices use a large number of electric wires for power supply and electric signal transmission. Generally, the electric wires have a structure in which a copper wire is the core and the outer periphery is covered with an insulator. Therefore, there is almost no elasticity in the electric wire itself. For this reason, for example, in a robot or the like, it is necessary to allow a sufficient wire length so as not to hinder the movement of the joints, and this is a practical problem in designing for miniaturization and weight reduction. Become.

  Especially in applications such as state-of-the-art humanoid robots and power assist devices that are attached to the human body to assist muscle strength, wires for moving the terminal motor via multi-degree-of-freedom joints and terminals are arranged. Many wires for transmitting electrical signals from various sensors are wired. And in order to raise the freedom degree of these wiring in a multi-degree-of-freedom joint, the request | requirement with respect to the electric wire comprised so that expansion-contraction is possible is increasing.

  On the other hand, in recent years, arm robots are often used as industrial robots. In this type of arm robot, depending on the end effector attached to the tip side of the robot arm (equivalent to a hand in the human body) or the driving method of the joint part of the robot arm, from the base side to the tip side of the robot arm In addition to the electric cable, it may be necessary to wire an air hose or a hydraulic hose for applying air pressure. When such cables and hoses are wired to the joints, the cables may be bent or disconnected. For this reason, the cables and hoses are temporarily extended outward at positions closer to the base end than the joints of the robot arms, and the cables are arranged in the outer space of the joints, and again inside the arm at positions closer to the tip than the joints. A wiring method such as introduction into the network is adopted. However, in the method of arranging the cable in the outer space of the robot arm, a space for loosening the cable is required around the joint portion of the robot arm.

  Further, for example, in Patent Document 1, a support rod is provided at the joint rotation center position in the joint portion of the robot arm, a cable is wound around the support rod, and the support rod on which the cable is wound is stored in the robot arm. Thus, a structure that prevents the cable from being bent or disconnected is disclosed. However, there is a possibility that functional deterioration (operation speed, accuracy, etc.) due to weight increase due to the separate provision of the support rod may occur. In some cases, a high-spec motor or the like is used in order to compensate for the deterioration of the function or the number of necessary members increases. In this case, the manufacturing cost increases. Furthermore, since the structure of the cable storage portion becomes complicated, there is a problem that it becomes very complicated when the cable is taken out and replaced when it is disassembled during wiring and maintenance of the robot arm during assembly. For this reason, even in the robot arm, there is an increasing demand for a telescopic electric transmission member that can avoid such a problem.

  As what respond | corresponds to the request | requirement with respect to such an electric transmission member, there exist a thing like patent document 2 and patent document 3, for example. Patent Document 2 and Patent Document 3 disclose a flexible printed circuit board and a molding method that can be stretched and formed into a so-called pleated shape in which shape portions curved to the right and left are alternately arranged. The flexible printed circuit boards disclosed in Patent Documents 2 and 3 described above use a thermoplastic resin such as LCP (Liquid Crystal Polymer) as a base film. And it is shape | molded so that it may become a substantially the same shape as a shaping | molding die by heating for 30 to 60 minutes at the temperature about several dozen degrees C-100 degreeC lower than the softening temperature of this resin.

  Note that the disclosure contents of Patent Document 2 and Patent Document 3 are described. In Patent Document 2, a plurality of plate-shaped molds each having a desired R formed at the tip thereof are provided, and the flexible printed circuit board has a fixed amount. While applying tension, the mold is moved and pressed against the flexible printed circuit board, whereby a plurality of curved portions are formed on the flexible circuit board. In this state, the flexible printed circuit board having a plurality of curved portions can be formed by heating the flexible printed circuit board.

  Further, in Patent Document 3, a desired R is formed on a plurality of guide pins provided in a jig, and these guide pins are arranged at intervals through which a flexible printed board can pass. Then, the flexible printed board having a plurality of curved portions can be formed by passing the flexible printed board between the guide pins, applying a certain tension to the flexible printed board, and heating the flexible printed board.

JP-A-8-57992 JP 2011-134484 A JP 2011-233822 A

  By the way, in the structure currently disclosed by patent document 2 or patent document 3, the pleat-shaped flexible printed circuit board which uses LCP as a material is formed in three dimensions. Therefore, since mounting after molding is difficult, there are many cases where the tip of the flexible printed circuit board becomes a plug-in type terminal portion. In order to form such a plug-in terminal at the tip, a thickness of 200 to 300 μm is generally required in accordance with the size of the opening of the receiving connector. Therefore, it is necessary to affix a reinforcement film on the base film of LCP. The reinforcing film is a material in which a polyimide film or a PET (Polyethylene Terephthalate) film is bonded to an adhesive.

  In addition, in order to take measures against electrical noise while maintaining expansion / contraction characteristics, a shield film for flexible printed circuit boards is used for a base material (insulating layer) made of LCP or a cover lay made of LCP. There is also a case of sticking together. Here, the surface of a base material or coverlay made of LCP has glossiness, but when a reinforcing film or a shield film is attached to such a surface, there is a problem of poor adhesion. For this reason, it is conceivable to use an adhesive material as an adhesive for the glossy LCP base material or coverlay surface, but such a material is a special material for high frequency use. So it is expensive. In general, various materials preferably have an alternative material in various aspects, but there is also a problem that the isotropic conductive adhesive of the shield film has no alternative material.

  In addition, when laminating a cover lay also made of LCP on a base material made of LCP and a single-sided base material provided with a copper foil layer on one side of the base material, the base constituting the single-sided base material Since the surface of the material is very smooth, sticking to the lower heating plate tends to occur. Therefore, it takes time and effort to peel off the adhered base material, making it difficult to produce efficiently. In contrast to this, in a single-sided base material that uses a polyimide film as a base material, fine unevenness is formed on the surface with a silica filler or the like called a lubricant, so that such sticking hardly occurs. Therefore, sticking to the lower heating plate as described above is a phenomenon peculiar to a base material made of LCP.

  In order to prevent such sticking to the lower heating platen, it is conceivable to arrange another sheet material on the surface of the lower heating platen. However, since lamination is a process of applying temperature and pressure, the surface shape of the sheet material may be transferred to the surface of the flexible printed board. Therefore, the surface of the sheet material also needs to have sufficient smoothness, and the cost increases accordingly. Further, when the sheet material as described above is interposed, the thermal conductivity is lowered by that amount. Therefore, there is also a problem that the process time in the lamination becomes long.

  As described above, for the reinforcing film and the shield film, while the adhesion of the base material made of LCP is good, it is possible to prevent sticking to the hot platen having a smooth surface. There is a need to solve the problem.

  The present invention has been made on the basis of the above circumstances, and prevents a substrate made of a liquid crystal polymer from sticking to a heating plate having a smooth surface, and at least one of a reinforcing film and a shielding film. In contrast, a flexible printed circuit board capable of at least one of achieving good adhesion of a substrate made of a liquid crystal polymer without using a special adhesive, and a flexible print An object is to provide a method for manufacturing a substrate.

  In order to solve the above problems, according to a first aspect of the present invention, a flexible printed circuit board having flexibility, a first insulating layer formed of a liquid crystal polymer that is a thermoplastic resin as a material, A second insulating layer formed on the surface of the first insulating layer, and arranged to cover the wiring layer on the side opposite to the first insulating layer, and formed from a thermoplastic resin. A first adhesive layer that is interposed between the wiring layer and the second insulating layer, adheres to each other, and is filled between the wirings to cover the wiring layer, and the wiring layer of the first insulating layer is opposite to the wiring layer There is provided a flexible printed circuit board comprising a first rough surface portion provided on a side surface and having a ten-point average roughness Rz having a roughness in a range of 1 μm to 5 μm.

  In addition, according to another aspect of the present invention, in the above-described invention, a terminal portion is provided on an end portion side of the first insulating layer, and the terminal portion is opposite to the wiring layer on the first insulating layer side. It is preferable to include a reinforcing layer that complements the thickness of the wiring layer and is made of resin, and a second adhesive layer that adheres to the first rough surface portion and adheres the reinforcing layer to the first rough surface portion. .

  Further, according to another aspect of the present invention, in the above-described invention, the second insulating layer is formed of a liquid crystal polymer, and there are ten points on the surface of the second insulating layer opposite to the wiring layer. A second rough surface portion having a roughness in the range of 1 μm to 5 μm in average roughness Rz is provided, and a shield layer including a metal thin film layer having electromagnetic wave shielding properties is bonded to the second rough surface portion. It is preferable that

  In another aspect of the present invention, in the above-described invention, it is preferable that the substrate main body portion continuous with the terminal portion is provided with a curved portion that is curved in at least one place.

  According to a second aspect of the present invention, there is provided a flexible printed circuit board having flexibility, the first insulating layer formed using a liquid crystal polymer that is a thermoplastic resin as a material, and the surface of the first insulating layer. A wiring layer that includes a plurality of wirings, a second insulating layer that is disposed so as to cover the wiring layer on the side opposite to the first insulating layer, and that is formed using a liquid crystal polymer as a material; and a wiring layer Between the first insulating layer and the second insulating layer, the first adhesive layer is filled between the wirings and covers the wiring layer, and the second insulating layer is provided on the surface opposite to the wiring layer. The ten-point average roughness Rz having a roughness within a range of 1 μm to 5 μm is bonded to the second insulating layer via the second roughness, and has an electromagnetic wave shielding property. A flexi characterized by comprising a shield layer comprising a metal thin film layer A bull printed circuit board is provided.

  According to a third aspect of the present invention, there is provided a method for manufacturing a flexible printed circuit board having flexibility, wherein a metal foil layer is formed on the front side of the first insulating layer formed from a liquid crystal polymer that is a thermoplastic resin. In the single-sided base material on which the metal foil layer is formed, the back surface side of the first insulating layer opposite to the metal foil layer is subjected to a roughening treatment, and the ten-point average roughness Rz is in the range of 1 μm to 5 μm. A first step of forming a first rough surface portion having a roughness, and a wiring having a plurality of wirings and having a desired pattern shape by patterning the metal foil layer before and after the first step. A coverlay comprising a second step of forming a layer, a second insulating layer formed from a thermoplastic resin, and a first adhesive layer laminated on the second insulating layer is positioned on the wiring layer, and By heating and pressing the coverlay, the first adhesive layer is And a third step of bonding the wiring layer and the first adhesive layer while filling between the wirings. A method of manufacturing a flexible printed board is provided.

  Furthermore, in another aspect of the present invention, in the above-described invention, a reinforcing film including a reinforcing layer made of resin and supplementing the thickness of the wiring layer, and a second adhesive layer laminated on the reinforcing layer, It is preferable to include a fourth step of adhering the second adhesive layer to the first rough surface portion by heating and pressurizing the reinforcing film in close contact with the end portion side of the first rough surface portion of the first insulating layer.

  According to another aspect of the present invention, in the above-described invention, the second insulating layer is formed of a liquid crystal polymer, and in the first step, the surface of the second insulating layer opposite to the wiring layer is provided. A metal roughening process is performed on the side to form a second rough surface portion having a roughness of 10-point average roughness Rz in the range of 1 μm to 5 μm, and a metal thin film layer having electromagnetic wave shielding properties is provided. It is preferable to include a fifth step of forming a shield layer by adhering the shield film to the second rough surface portion, heating and pressing the shield film, and bonding the shield film to the second rough surface portion. .

  Another aspect of the present invention is the above-described invention, wherein the flexible printed circuit board formed by at least the third step is subjected to thermoforming in a state where at least one portion is curved, It is preferable to include a sixth step of forming the curved portion after the thermoforming.

  According to a fourth aspect of the present invention, there is provided a method of manufacturing a flexible printed board having flexibility, the second insulating layer formed of a liquid crystal polymer that is a thermoplastic resin as a material, and the second insulating layer. The surface of the second insulating layer opposite to the first adhesive layer in the cover lay including the first adhesive layer laminated on the layer is subjected to a roughening treatment, and the ten-point average roughness Rz is A first step of forming a second rough surface portion having a roughness within a range of 1 μm to 5 μm, and a first insulating layer formed of a liquid crystal polymer, which is a thermoplastic resin, before and after the first step. Of the single-sided base material on which the metal foil layer is formed on the front side, a second step of forming a wiring layer having a plurality of wirings and having a desired pattern shape by patterning the metal foil layer; Position the coverlay on the wiring layer and A shield film comprising a third step of bonding the wiring layer and the first adhesive layer while filling the first adhesive layer between the wirings by heating and pressurizing, and a metal thin film layer having electromagnetic wave shielding properties A second step of forming a shield layer by adhering the shield film to the second rough surface portion, heating and pressurizing the shield film, and bonding the shield film to the second rough surface portion. A method for manufacturing a flexible printed circuit board is provided.

  According to the present invention, it is possible to prevent sticking of a base material made of a liquid crystal polymer to a heating plate having a smooth surface, and special adhesion to at least one of a reinforcing film and a shield film. Even without using an agent, at least one of achieving good adhesion of a substrate made of a liquid crystal polymer can be achieved.

It is a perspective view which shows an example of a structure of the flexible printed circuit board concerning one embodiment of this invention after shaping | molding. It is a partial sectional side view which shows an example of a structure of the flexible printed circuit board which concerns on one embodiment of this invention before shaping | molding or before shaping | molding. It is a front sectional view showing an example of composition of a flexible printed circuit board after fabrication or a flexible printed circuit board before fabrication, and is a figure showing the state where it cut along the AA line of FIG. It is a front sectional view showing an example of the composition of the flexible printed circuit board after forming or the flexible printed circuit board before forming, and is a figure showing the state where it cut along the BB line of FIG. It is a figure which concerns on a 1st process and shows the image of embossing. It is a sectional side view which shows the state which concerns on the 2nd process and formed the single-sided base material which has a wiring layer. It is a figure which shows the image which concerns on a 3rd process and laminates | stacks a coverlay on a single-sided base material, (a) shows the structure of the single-sided base material and coverlay before lamination, (b) uses a laminating apparatus. FIG. It is a perspective view which shows the image which concerns on a 4th process and a 5th process, and bonds a reinforcement film and a shield film with respect to an intermediate product. It is front sectional drawing which shows the image which concerns on a 4th process and a 5th process, and bonds a reinforcement film and a shield film with respect to an intermediate product. It is front sectional drawing which shows the image after having bonded a reinforcement film and a shield film with respect to the intermediate product in the 4th process and the 5th process. It is a figure which concerns on a 6th process and shows the state which set the flexible printed circuit board before shaping | molding to the jig | tool.

  Hereinafter, flexible printed circuit boards 10A and 10B according to an embodiment of the present invention will be described below. In the following description, an XYZ orthogonal coordinate system may be used for explanation. Of these, the X direction is the longitudinal direction of the flexible printed boards 10A and 10B, the X1 side is the right side of FIG. 1, and the X2 side is the left side. Further, the Y direction is the width direction of the flexible printed boards 10A and 10B, the Y1 side is the left front side of the paper surface in FIG. 1, and the Y2 side is the back right side of the paper surface. The Z direction is the thickness direction of the flexible printed boards 10A and 10B, Z1 is the back side of the paper surface in FIG. 2, and Z2 is the front side of the paper surface.

<Configuration of flexible printed circuit board>
FIG. 1 is a perspective view showing an example of the configuration of the flexible printed circuit board 10A after molding. FIG. 2 is a side sectional view showing an example of the configuration of the flexible printed circuit boards 10A and 10B after molding or before molding, with the middle omitted. FIG. 3 is a front cross-sectional view showing an example of the configuration of the flexible printed circuit board 10A after molding or the flexible printed circuit board 10B before molding, and shows a state cut along the line AA in FIG. 4 is a front sectional view showing an example of the configuration of the flexible printed circuit board 10A after molding or the flexible printed circuit board 10B before molding, and shows a state cut along the line BB in FIG. is there.

  As shown in FIG. 1, the flexible printed circuit board 10 </ b> A after molding is provided with a substrate body 11 and terminal portions 12. The substrate main body 11 is provided with a plurality of bending portions 13 so that the directions of the curves drawn by the bending portions 13 are switched alternately. Therefore, the molded flexible printed circuit board 10A is formed in a pleated shape (accordion shape). Moreover, the terminal part 12 is also provided in 10 A of flexible printed circuit boards. The terminal portion 12 is a portion where the conductive portion is exposed on the surface and is inserted into the opening portion of the external connector. Hereinafter, details of the configuration of the flexible printed circuit board 10A will be described.

  As shown in FIGS. 2 to 4, the flexible printed circuit board 10 </ b> A includes an insulating layer 21, a wiring layer 22, an adhesive layer 31, a cover layer 32, an adhesive layer 41, a reinforcing layer 42, a shield layer 51, and the like. It has. Among these, the substrate main body 11 includes an insulating layer 21, a wiring layer 22, an adhesive layer 31, and a cover layer 32. The terminal portion 12 includes an insulating layer 21, a wiring layer 22, and a shield layer 51.

  Among the above-described configurations, the insulating layer 21 and the wiring layer 22 are portions that constitute a single-sided base material 20 to be described later, and are portions that are present in both the substrate main body portion 11 and the terminal portion 12. The insulating layer 21 is a portion made of, for example, a film-like liquid crystal polymer (LCP) having a thickness of 50 μm. The insulating layer 21 corresponds to the first insulating layer. The LCP includes a type composed of a polycondensate of ethylene terephthalate and parahydroxybenzoic acid, a type composed of a polycondensate of phenol and phthalic acid and parahydroxybenzoic acid, and 2,6-hydroxynaphthoic acid. There is a type composed of a polycondensate of acid and parahydroxybenzoic acid, but any type may be used.

  The wiring layer 22 is provided on the front surface side (Z1 side surface side) of the insulating layer 21. The wiring layer 22 is formed by patterning a copper foil layer having a predetermined thickness of, for example, 12 μm into a desired pattern shape. Thus, the plurality of copper wirings 221 (corresponding to the wirings) are formed.

  Here, a rough surface portion 211 (corresponding to the first rough surface portion) is provided on the back surface side (the surface side on the Z2 side) of the insulating layer 21. The rough surface portion 211 is a portion roughened from the front surface side of the insulating layer 21 by performing predetermined processing or processing on the back surface side of the insulating layer 21. The rough surface portion 211 is intended to prevent sticking to a lower heating plate 160 (see FIG. 7B), which will be described later, and to enhance the adhesion when the reinforcing film 40 described above is attached. It is a part of.

  The roughness of the rough surface portion 211 is required to achieve at least one of prevention of sticking to the lower heating plate 160 and improvement of adhesion of the reinforcing film 40. Any roughness may be used as long as it can achieve one. When achieving both prevention of sticking to the lower heating plate 160 and improvement in adhesion of the reinforcing film 40, the rough surface portion 211 has a ten-point average roughness Rz in the range of 1 μm to 5 μm. It is preferable to be within. Among these, it has been confirmed that the peel strength can be further enhanced when the 10-point average roughness Rz is in the range of 1.8 μm to 3.2 μm (described later).

  The adhesive layer 31 and the cover layer 32 are portions formed from a cover lay 30 to be described later, and are portions that are present in the substrate main body portion 11 although they are not present in the terminal portion 12. Among these, the adhesive layer 31 is provided so as to cover the wiring layer 22, and the cover layer 32 is bonded via the adhesive layer 31. The adhesive layer 31 corresponds to the first adhesive layer. The adhesive layer 31 may be, for example, an epoxy-based adhesive, but an adhesive made of other materials may be used as long as the adhesiveness is good. Moreover, although the thickness of the contact bonding layer 31 is provided, for example in 15 micrometers, what kind of thickness may be sufficient as it.

  The adhesive layer 31 is preferably low-elasticity so as not to hinder subsequent molding. Specifically, since the elastic coefficient of the liquid crystal polymer (LCP) film is 3 to 4 GPa, the adhesive having an elastic coefficient of less than half of this elastic coefficient (or 2 GPa or less when the elastic coefficient is 4 GPa at the maximum). By applying to the adhesive layer 31, it is possible to bond together without affecting the moldability. As will be described later, when the flexible printed circuit board 10B before molding is molded, the temperature is about 200 ° C. and heated for about 30 minutes. Therefore, it is preferable that the heat history as described above does not significantly deteriorate the adhesiveness and the electrical insulation characteristics.

  The cover layer 32 corresponds to the second insulating layer. The cover layer 32 is a portion made of, for example, a film-like LCP (Liquid Crystal Polymer) having a thickness of 50 μm, like the insulating layer 21. The cover layer 32 may be composed of the same type of LCP as the insulating layer 21 or may be composed of a different type of LCP.

  Here, a rough surface portion 321 similar to the rough surface portion 211 is also provided on the surface side of the cover layer 32 (the surface side on the Z1 side). The rough surface portion 321 is a portion roughened by subjecting the surface side of the cover layer 32 to predetermined processing or processing in the same manner as the insulating layer 21. The rough surface portion 321 is a portion for improving the adhesion with the shield layer 51. The roughness of the rough surface portion 321 is the same as the roughness of the rough surface portion 211 described above. That is, any roughness may be used as long as the adhesion of the shield layer 51 can be improved. The roughness of the rough surface portion 321 is preferably such that the ten-point average roughness Rz is in the range of 1 μm to 5 μm. Among these, it has been confirmed that the peel strength can be further enhanced when the 10-point average roughness Rz is in the range of 1.8 μm to 3.2 μm (described later).

  Further, the adhesive layer 41 and the reinforcing layer 42 are portions formed from a reinforcing film 40 described later, and are portions that are present in the terminal portion 12 of the flexible printed board 10A. Among these, the adhesive layer 41 is a portion that is bonded to the rough surface portion 211 of the insulating layer 21, and the reinforcing layer 42 is bonded via the adhesive layer 41. The adhesive layer 41 corresponds to the second adhesive layer. The material of the adhesive layer 41 may be the same material as the adhesive layer 31 described above, but may be a separate material. The reinforcing layer 42 is formed of a film-like member having a predetermined thickness made of polyimide or PET (Polyethylene Terephthalate).

  Here, since the terminal part 12 is a part inserted in the opening part of an external connector as mentioned above, generally predetermined thickness of 200 micrometers-300 micrometers is required. Therefore, the adhesive layer 41 and the reinforcing layer 42 (among them, the reinforcing layer 42 in particular) have large thicknesses that complement the thicknesses of the insulating layer 21 and the wiring layer 22.

  Note that the thickness of the adhesive layer 41 is, for example, 15 μm, like the adhesive layer 31 described above. Moreover, as shown in FIG. 3, it is normal that the conductive film 61 is formed in the surface of each copper wiring 221 in the terminal part 12 by the plating process etc. As shown in FIG. The conductive film 61 has a thickness of 12 μm, for example, but may be any thickness. Therefore, the thickness of the reinforcing layer 42 is approximately the same as the thickness of the insulating layer 21, the wiring layer 22, the conductive coating 61, and the adhesive layer 41 from the above-mentioned 200 μm to 300 μm. It has become a part.

  The shield layer 51 is a portion that exists in the substrate main body 11. The shield layer 51 is a portion that prevents external noise from entering the internal signal line and prevents noise in the internal signal line from being released to the outside. As the shield film 50 for constituting the shield layer 51, a thin film conductive film can be used. In such a thin film conductive film, one surface side of the metal thin film layer is covered with a protective layer having electrical insulation, such as PET or polyimide, and the other surface side is covered with a conductive adhesive layer. Things. The metal thin film layer is a portion where the metal is formed in a thin film, and the thickness thereof is very thin, for example, 0.1 μm. In addition, the thickness of the metal thin film layer is not limited to 0.1 μm, and various thicknesses can be used as long as the electromagnetic wave shielding property is maintained while maintaining flexibility. Practically, it can be appropriately selected within a range of 0.05 μm to 2 μm, for example.

  Such thin metal thin film layers are generally formed by physical vapor deposition (PVD), such as vacuum deposition, sputtering, ion plating, or chemical vapor deposition (CVD). ) And the like. In addition, the whole thickness of an electroconductive film is provided in thickness, such as 5-20 micrometers, for example. As a metal material constituting the metal thin film layer, various metal materials such as silver, aluminum, copper, gold, nickel, chromium and zinc can be used. Among these, it is preferable to form the metal thin film layer using inexpensive aluminum or highly reliable silver.

  As the conductive adhesive layer of the thin film conductive film, an isotropic conductive adhesive layer can be used, but an anisotropic conductive adhesive layer may be used. The anisotropic conductive adhesive layer is formed by dispersing conductive fillers having conductivity as described above in an adhesive made of resin, and pressurizing the conductive fillers by bringing them into contact with each other. It is intended to develop conductivity in the direction. However, it may be configured to have anisotropic conductivity, for example, by self-condensing conductive fillers without applying pressure. The adhesive for the anisotropic conductive adhesive layer may be an adhesive layer formed of the same material as the conductive paste as described above.

  As such a thin film conductive film, for example, the SF-PC series manufactured by Tatsuta Electric Wire Co., Ltd. can be mentioned, but a film having other configurations may be used as long as electromagnetic noise can be shielded.

<About manufacturing method of flexible printed circuit board 10A>
Then, the manufacturing method of 10 A of flexible printed circuit boards of the structure as mentioned above is demonstrated below. In the following description, the first to sixth steps are sequentially described, but it is needless to say that various steps other than these may exist.

(1) First Step: Formation of Rough Surface Portion 211 and Rough Surface Portion 321 FIG. 5 is a diagram showing an image of embossing related to the first step. When forming the rough surface portion 211 and the rough surface portion 321, generally, an embossing apparatus 100 as shown in FIG. 5 can be used. The embossing apparatus 100 includes a heater 110, an embossing roll 120, and a driven roll 130. The heater 110 is a portion that heats the single-sided copper-clad laminate 20S without unevenness or the coverlay film 30S without unevenness using a heater such as a far-red heater, a near-red heater, or a ceramic heater. Then, the single-sided copper-clad laminate 20S and the coverlay film 30S are raised above the softening point temperature.

  After being heated by the heater 110, the single-sided copper-clad laminate 20 </ b> S and the coverlay film 30 </ b> S are sent between the embossing roll 120 and the driven roll 130. The embossing roll 120 is a roller provided with an embossing surface 121 having minute irregularities on the surface. The unevenness on the embossed surface 121 is transferred to the surface of the single-sided copper-clad laminate 20S or the coverlay film 30S. Further, the driven roll 130 is a roller that is in close proximity to the embossing roll 120, and can press the single-sided copper clad laminate 20 </ b> S and the coverlay film 30 </ b> S sent between the embossing roll 120 with a predetermined pressure. Yes.

  With the embossing apparatus 100 having such a configuration, the insulating layer 21 of the single-sided copper-clad laminate 20S and the cover layer 32 of the coverlay film 30S heated to the softening point or higher are disposed between the embossing roll 120 and the driven roll 130. By applying pressure, the insulating layer 21 and the cover layer 32 are formed with a rough surface portion 211 or a rough surface portion 321 having a desired roughness.

  The method for forming the rough surface portion 211 and the rough surface portion 321 is not limited to embossing. For example, by laminating a copper foil having a roughness corresponding to the roughness described above on the back side of the insulating layer 21 or the cover layer 32, and removing the copper foil by etching or the like, the insulating layer 21 or the cover is removed. A replica of the copper foil (unevenness with the surface roughness of the copper foil transferred to the insulating layer) may be transferred to the back side of the layer 32. Further, the embossing device 100 is not limited to the above-described configuration. For example, without using a roller, a flat metal mold having an embossed surface similar to the above-described embossed surface 121 is used to apply pressure and heat. It is good also as composition to do.

(2) Second Step: Formation of Wiring Layer 22 Having Circuit Pattern Shape FIG. 6 is a side sectional view showing a state in which the single-sided base material 20 having the wiring layer 22 is formed. As shown in FIG. 6, after the first step described above, a wiring layer 22 having a desired circuit pattern shape is formed. When the wiring layer 22 is formed, it is formed by using a normal photofabrication technique such as etching. Thereby, the single-sided base material 20 in which the wiring layer 22 having a plurality of copper wirings 221 as shown in FIG. 6 exists is formed.

  Note that the flexible printed circuit board 10A in the present embodiment may be etched in a state where the single-sided base material 20 is cut to a predetermined length, and is cut to a predetermined length after etching. It is good as a thing. The second step may be performed after the first step, but may be performed before the first step.

(3) Third Step: Lamination of Cover Lay 30 FIG. 7 is a diagram showing an image of laminating the cover lay 30 on the single-sided substrate 20. 7A shows a configuration of the single-sided base material 20 and the coverlay 30 before lamination, and FIG. 7B is a diagram showing a state of laminating using the laminating apparatus 150. FIG. As shown in FIG. 7A, the coverlay 30 is positioned on the front surface side (Z1 side surface side) of the single-sided base material 20. Then, after performing a predetermined alignment, the cover lay 30 is bonded to the single-sided base material 20 using the laminating apparatus 150.

  Here, the laminating apparatus 150 includes a lower heating plate 160 and an upper heating plate 170, and also includes a pressing mechanism and a heating mechanism (not shown). Therefore, the back surface side (Z2 side surface side; rough surface portion 211 side) of the single-sided base material 20 is placed on the lower heating plate 160, and the adhesive layer 31 of the coverlay 30 is positioned so as to cover the wiring layer 22, The adhesive material component of the adhesive layer 31 is filled between the copper wirings 221 of the wiring layer 22 after lamination. Further, a resin cushion material 180 such as a high melting point polyolefin or a fluororesin is disposed on the cover lay 30.

  In this state, laminating is performed by pressing and heating the single-sided base material 20 and the coverlay 30 between the lower heating platen 160 and the upper heating platen 170. The pressurizing pressure is, for example, 1 to 4 MPa, and the heating temperature is, for example, 130 to 180 ° C. In this pressurization and heating, the rough surface portion 211 comes into direct contact with the lower heating platen 160, but it is possible to prevent sticking between them, thereby realizing a highly productive laminating process. Yes. In addition, let the product after sticking be the intermediate product C1.

  In addition, after lamination, surface treatment such as electroless gold plating is performed on a portion of the single-sided base material 20 that is not covered with the coverlay 30 (for example, the terminal portion 12) as necessary. In this process, the conductive film 61 is formed on each copper wiring 221 of the terminal portion 12.

(4) Fourth Step and Fifth Step: Bonding of Reinforcing Film 40 and Shield Film 50 FIG. 8 relates to the fourth step and the fifth step, and the reinforcing film 40 and the shielding film 50 are applied to the intermediate product C1. It is a perspective view which shows the image to bond. FIG. 9 is a front cross-sectional view illustrating an image in which the reinforcing film 40 and the shield film 50 are bonded to the intermediate product C1 in the fourth step and the fifth step. FIG. 10 is a front sectional view showing an image after the reinforcing film 40 and the shield film 50 are bonded to the intermediate product C1 in the fourth step and the fifth step.

  9 and FIG. 10, the left and right sides show cross-sectional shapes at different parts, the left side shows the cross-sectional shape at the terminal portion 12 side, and the right side shows the cross-sectional shape at the substrate main body portion 11 side. Further, for convenience of explanation, the fourth step is the bonding of the reinforcing film 40 and the fifth step is the bonding of the shield film 50. However, the fourth step may be performed before the fifth step. The process may be performed before the fourth process.

  As shown in FIGS. 8 and 9, the reinforcing film 40 and the shield film 50 are bonded to the intermediate product C1. Although the reinforcing film 40 is affixed to the terminal part 12, this affixing part (position of the terminal part 12) is a part which does not become an obstacle when shape | molding in a bellows form later. In addition, the shield film 50 is placed on the cover layer 32 to be bonded.

  When the reinforcing film 40 and the shield film 50 are bonded together, the same laminating apparatus 150 used in the third step is used in each bonding. In this bonding, since the rough surface portion 211 is provided on the back surface side (Z2 side surface side) of the insulating layer 21, it is possible to improve the adhesion between the reinforcing film 40 and the adhesive layer 41. Become. Further, since the rough surface portion 211 exists, it is possible to prevent the insulating layer 21 from sticking to the lower heating platen 160 at a portion where the reinforcing film 40 is not located. Further, since the rough surface portion 321 is provided on the surface side (the surface side on the Z1 side) of the cover layer 32, the adhesion with the shield film 50 can be improved.

  When the above bonding is performed, an adhesive layer 41 and a reinforcing layer 42 are formed from the reinforcing film 40, and a shield layer 51 is formed from the shield film 50.

  In addition, after performing such affixing, it processes using a metal mold | die etc. so that it may become a desired external shape as needed. Even when processing such an outer shape, the adhesion of the adhesive layer 41 and the shield layer 51 is improved, so that these end portions are prevented from peeling off from the insulating layer 21 and the cover layer 32, The process can be executed. When the above-described pasting is performed, the flexible printed circuit board 10B in a state before molding is formed.

(5) Sixth Step: Heat Molding of Flexible Printed Circuit Board 10B FIG. 11 is a diagram showing a state where the flexible printed circuit board 10B before molding is set on the jig 400 in the sixth process. As shown in FIG. 11, the flexible printed circuit board 10 </ b> B before molding is set on the jig 400 while being aligned. The jig 400 is made of a metal such as SUS304. The jig 400 is provided with a tip fixing member 410. The distal end fixing member 410 is provided with a distal end receiving portion 411 for placing the distal end side of the flexible printed circuit board 10B, and a latch pin 412 to be inserted into a hole portion on the distal end side of the flexible printed circuit board 10B (not shown). Is provided.

  A hole on the tip side of the flexible printed circuit board 10B is inserted into the latch pin 412, and in this state, the flexible printed circuit board 10B is meandered along the jig pin 420 arranged at a predetermined position of the jig 400. The setting of the flexible printed circuit board 10B to the jig 400 is completed. After the setting, a certain tension is applied to the rear end side of the flexible printed circuit board 10B. In this state, the flexible printed circuit board 10B containing the LCP material which is thermoplastic is heated in an oven or the like, thereby having a plurality of curved portions 13 as shown in FIG. A printed circuit board 10A is formed.

  Here, the thermoforming in an oven or the like is performed by heating at 200 ° C. for 30 minutes, for example. In the case of thermoforming in this way, thermoforming is performed in a state where the setting position of the flexible printed circuit board 10B and the tension at the time of setting on the jig 400 are stable. Therefore, in the flexible printed circuit board 10A after molding, the product shape is stable, and the curved portion 13 is present at the target position.

  As shown in FIG. 1, the flexible printed circuit board 10A is provided in an elongated shape. In the present embodiment, the flexible printed circuit board 10B before molding has a length (dimension in the X direction) of, for example, 300 mm. On the other hand, when the flexible printed circuit board 10A after molding is molded into a pleat shape (bellows shape) so that the radius of the curved portion 13 is 4 mm, the length is, for example, about 150 mm. However, the dimension example is not limited to this, and various dimensions can be set (the same applies to other dimension examples).

  Moreover, after this shaping | molding, unnecessary parts, such as the front end side positioned by the front-end | tip fixing member 410 grade | etc., Are cut out of the flexible printed circuit board 10A after shaping | molding as needed, and a final product is completed. As a method of cutting such unnecessary portions, a hole portion into which the latch pin 412 is inserted is diverted in the flexible printed circuit board 10A, the starting point side is positioned, and the opposite side is positioned by abutment or the like. Then, it can be cut using a cutting jig such as a pinnacle or a mold. However, methods other than those described above may be used for cutting unnecessary portions. Examples of such methods include laser cutting using a laser and router cutting using a router bit.

  When the reinforcing film 40 is attached to the back surface side (Z2 side surface side) of the insulating layer 21 of the single-sided base material 20 without attaching the shield layer 51 or the like to the coverlay 30 side, the rough surface portion 321 is not formed. Instead, only the rough surface portion 211 may be formed. In this case, the presence of the rough surface portion 211 can ensure adhesion between the laminating apparatus 150 and the laminating apparatus 150 when the laminating apparatus 150 laminates the cover lay 30 or bonds the reinforcing film 40 together. It becomes possible to prevent the insulating layer 21 from sticking to the lower heating platen 160.

  As described above, the flexible printed board 10A as shown in FIG. 1 is formed.

<Experimental results>
Next, the experimental result regarding this Embodiment is demonstrated. First, Table 1 shows the experimental results of the relationship between the roughness of the surface of the LCP film and the sticking of the reinforcing film. As an LCP film in this experiment, an LCP film CT-Z manufactured by Kuraray Co., Ltd. was used, and its thickness was 50 μm. Also, as the reinforcing film, Nikaflex SAFW manufactured by Nikkan Kogyo Co., Ltd. is used as the adhesive layer, the thickness is 40 μm, and the polyimide film (Kapton 200H / V manufactured by Toray DuPont Co., Ltd.) is used as the insulating layer. 50 μm. Further, using the same apparatus as the laminating apparatus 150, the LCP film and the reinforcing film were hot-pressed. The pressure applied to the LCP film and the reinforcing film was 2 MPa, the heating temperature was 140 ° C., and heating and pressurization were performed for 2 minutes.

  Moreover, about formation of the unevenness | corrugation of the surface of a LCP film, the copper foil which has a surface by which ten-point average roughness Rz is already known is hot-pressed to an LCP film, and copper foil is removed by an etching after that. Formed by. Therefore, in this experiment, the ten-point average roughness Rz of the transfer surface of the copper foil is the ten-point average roughness Rz of the surface of the LCP film. In addition, the peel strength is measured by measuring peel strength in accordance with ISO 29862 (peeling tape peeling 90 ° peel test), and the peel strength measurement is a universal product manufactured by Shimadzu Corporation. A measuring device called a tester AGS-X was used.

  As can be seen from the results in Table 1, when the ten-point average roughness Rz is 1 μm or more, the peel strength is 0.8 kN / m or more, and the reference peel strength of 0.8 kN / m is cleared. Even when the ten-point average roughness Rz exceeds 5 μm, the peel strength can be obtained as a high value sufficiently clearing the reference peel strength, but the roughness of the LCP film varies due to the roughness (film thickness). It is also necessary to consider the filling of the adhesive to such roughness. Therefore, the ten-point average roughness Rz is preferably in the range of 1 μm to 5 μm.

  In addition, from the result of Table 1, when the ten-point average roughness Rz is in the range of 1.8 μm to 3.2 μm, the peel strength exceeds 1.0 kN / m, and it becomes more difficult to peel off. Even more preferred.

  Then, it shows in Table 2 about the experimental result done about the roughness of the surface of a LCP film, and the relationship of sticking to a heat | fever board (lower heat | fever board). As an LCP film in this experiment, an LCP film CT-Z manufactured by Kuraray Co., Ltd. was used, and its thickness was 50 μm. Further, the surface roughness Rz of the surface of the laminating apparatus 150 to which the LCP film adheres (the lower heating platen 160) is 2 μm. Moreover, the method similar to the experiment in Table 1 was used about formation of the unevenness | corrugation of the surface of a LCP film. The pressure applied to the LCP film was 2 MPa, the heating temperature was 160 ° C., and heating and pressurization were performed for 2 minutes.

  From the above experimental results, it was confirmed that sticking to the lower heating plate 160 does not occur when the ten-point average roughness Rz is 1 μm to 3 μm. When the ten-point average roughness Rz exceeds 5 μm, as described in Table 1, the peel strength can be obtained as a high value sufficiently clearing the standard peel strength, but due to the roughness. Variations in the thickness of the LCP film (thickness variation) occur, and it is necessary to consider the filling of the adhesive to such roughness. Therefore, the ten-point average roughness Rz is preferably in the range of 1 μm to 5 μm.

  In addition, based on the results of both Table 1 and Table 2, when the ten-point average roughness Rz is in the range of 1.8 μm to 3.2 μm, the peel strength exceeds 1.0 kN / m. Since it will be in the state where it is hard to peel off and sticking to the lower heating plate 160 does not occur, it is more preferable.

<About effect>
According to the flexible printed circuit board 10A having the above configuration and the method for manufacturing the flexible printed circuit board 10A, the following effects are produced.

  That is, the flexible printed circuit board 10 </ b> A includes an insulating layer 21 made of LCP (liquid crystal polymer), which is a thermoplastic resin, and a wiring layer that is formed on the surface of the insulating layer 21 and includes a plurality of copper wirings 221. 22. Further, the wiring layer 22 is disposed so as to cover the side opposite to the insulating layer 21 (Z1 side), and the cover layer 32 formed of a thermoplastic resin is interposed between the wiring layer 22 and the cover layer 32. And an adhesive layer 31 filled between the plurality of copper wirings 221 and covering the wiring layer 22. Further, the surface of the insulating layer 21 opposite to the wiring layer 22 (Z2 side) is provided with a rough surface portion 211 having a roughness of 10-point average roughness Rz in the range of 1 μm to 5 μm. .

  Therefore, for example, when laminating the coverlay 30 to the single-sided base material 20, the rough surface portion 211 of the insulating layer 21 directly contacts the lower heating plate 160 of the laminating apparatus 150. However, sticking between the rough surface portion 211 and the lower heating plate 160 can be prevented. Therefore, a highly productive laminating process can be realized.

  In the present embodiment, the terminal portion 12 is provided on the end portion side of the insulating layer 21, but the terminal portion 12 is connected to the insulating layer 21 on the side opposite to the wiring layer 22 (Z2 side). A reinforcing layer 42 that complements the thickness of the wiring layer 22 and is made of resin, and an adhesive layer 41 that is in close contact with the rough surface portion 211 and adheres the reinforcing layer 42 to the rough surface portion 211 are provided.

  For this reason, the presence of the rough surface portion 211 can improve the adhesion (adhesiveness) of the adhesive layer 41 to the insulating layer 21 by causing an anchor effect or the like. Therefore, the adhesive layer 41 (reinforcing layer 42) can be made difficult to peel off from the insulating layer 21. Therefore, it is not necessary to use an expensive (special) adhesive having adhesiveness to the glossy LCP film, and the versatility of the adhesive can be improved. Moreover, an alternative material can also be secured by increasing the versatility of the adhesive.

  Furthermore, in the present embodiment, the cover layer 32 is made of a liquid crystal polymer, and the surface of the cover layer 32 opposite to the wiring layer 22 (Z1 side) has a ten-point average roughness Rz. A rough surface portion 321 having a rough surface within a range of 1 μm to 5 μm is provided. In addition, a shield layer 51 including a metal thin film layer having electromagnetic wave shielding properties is bonded to the rough surface portion 321. For this reason, the presence of the rough surface portion 321 can improve the adhesion (adhesiveness) of the shield layer 51 to the cover layer 32 by causing an anchor effect or the like. Therefore, it is possible to make it difficult for the shield layer 51 to be peeled off from the cover layer 32. Therefore, it is not necessary to use an expensive adhesive having adhesiveness to the glossy liquid crystal polymer film, and the versatility of the adhesive can be improved. Moreover, an alternative material can also be secured by increasing the versatility of the adhesive.

  In the present embodiment, the substrate body 11 is provided with a curved portion 13 that is curved in at least one place. For this reason, since flexible printed circuit board 10A is provided in a pleat shape, it becomes possible to give elasticity. Moreover, since it can shape | mold in a pleat shape, preventing sticking to each site | part of the jig | tool 400 at the time of shaping | molding, it becomes possible to improve productivity.

<Modification>
Although one embodiment of the present invention has been described above, the present invention can be variously modified in addition to this. This will be described below.

  In the above-described embodiment, the flexible printed circuit board 10A is provided in a pleated shape. However, the flexible printed circuit board is not limited to the configuration provided in the pleat shape, and the present invention is naturally applied to other shapes (for example, one having only one straight shape or a curved portion). Is possible.

  In the above-described embodiment, the rough surface portion 211 is formed over the entire back surface side (Z2 side surface side) of the insulating layer 21, and the rough surface portion 321 is the front surface side (Z1 side) of the cover layer 32. Of the entire surface). However, the rough surface portion 211 may be formed on at least a part (for example, an edge portion) of the back surface side (Z2 side surface side) of the insulating layer 21, and similarly, the rough surface portion 321 is formed on the cover layer 32. It suffices if it is formed on at least a part (for example, an edge or the like) on the surface side (Z1 side surface side).

  In the above-described embodiment, the flexible printed circuit board 10 </ b> A includes the adhesive layer 41 and the reinforcing layer 42. However, the flexible printed circuit board may be configured not to include at least one of the adhesive layer 41 and the reinforcing layer 42. In the case where the flexible printed board does not include the adhesive layer 41 and the reinforcing layer 42, the rough surface portion 211 may be omitted on the back surface side (Z2 side surface side) of the insulating layer 21.

  In the above-described embodiment, the flexible printed board 10 </ b> A includes the shield layer 51. However, the flexible printed circuit board may be configured not to include the shield layer 51. In the case where the flexible printed circuit board does not include the shield layer 51, the rough surface portion 321 may be omitted on the surface side (the surface side on the Z1 side) of the cover layer 32.

  In addition, the flexible printed circuit board 10A in the above-described embodiment may have other metal thin film layers, resin layers, adhesive layers, and the like.

  Further, in the above-described embodiment, the curved portions 13 in the flexible printed circuit board 10A may be the same size at the same pitch, or may be formed at different pitches or partially at different pitches. In addition, the size (radius etc.) of a certain curved portion may be different from the size (radius etc.) of another curved portion. Moreover, you may combine the thing in which the some bending part is arrange | positioned by another pitch and magnitude | size with respect to what the some bending part is arrange | positioned with a certain pitch and magnitude | size.

  Moreover, in the above-mentioned embodiment, as the roughening process for forming the rough surface portion 211 and the rough surface portion 321, embossing or a replica of copper foil is transferred. However, the roughening treatment is not limited to these, and other methods may be used. Other methods include physical or chemical blast treatment, plasma treatment, and the like.

DESCRIPTION OF SYMBOLS 10A, 10B ... Flexible printed circuit board, 11 ... Board | substrate main-body part, 12 ... Terminal part, 13 ... Curve part, 20 ... Single-sided base material, 20S ... Single-sided copper clad laminated board, 21 ... Insulating layer (corresponding to 1st insulating layer) , 22 ... wiring layer, 30 ... coverlay, 30S ... coverlay film, 31 ... adhesive layer (corresponding to the first adhesive layer), 32 ... cover layer (corresponding to the second insulating layer), 40 ... reinforcing film, 41 ... Adhesive layer (corresponding to the second adhesive layer), 42 ... reinforcing layer, 50 ... shield film, 51 ... shield layer, 61 ... conductive coating, 100 ... embossing device, 110 ... heater, 120 ... embossing roll, 121 ... embossing Surface 130, driven roll 150, laminating device 160, lower heating plate 170, upper heating plate 180, cushioning material 211 211 rough surface portion (corresponding to the first rough surface portion) 221 copper wiring (corresponding to wiring) ), 321 ... corresponding to the rough surface portion (second rough surface portion), 400 ... jig, 410 ... tip fixing member, 411 ... tip receiving portion, 412 ... hooking pin 420 ... jig pins, C1 ... intermediate product

Claims (10)

A flexible printed circuit board having flexibility,
A first insulating layer formed from a liquid crystal polymer that is a thermoplastic resin;
A wiring layer formed on the surface of the first insulating layer and including a plurality of wirings;
A second insulating layer formed from a thermoplastic resin and disposed so as to cover the wiring layer on the side opposite to the first insulating layer;
A first adhesive layer that is interposed between the wiring layer and the second insulating layer to bond them, and is filled between the wirings to cover the wiring layer;
A first rough surface portion provided on a surface of the first insulating layer opposite to the wiring layer, and having a ten-point average roughness Rz in a range of 1 μm to 5 μm;
A flexible printed circuit board comprising: The flexible printed circuit board according to claim 1,
A terminal portion is provided on the end side of the first insulating layer,
The terminal portion is
A reinforcing layer made of resin and complementing the thickness of the first insulating layer and the wiring layer on the opposite side of the wiring layer;
A second adhesive layer that adheres to the first rough surface portion and adheres the reinforcing layer to the first rough surface portion;
A flexible printed circuit board comprising: A flexible printed circuit board according to claim 1 or 2,
The second insulating layer is formed from a liquid crystal polymer,
A surface of the second insulating layer opposite to the wiring layer is provided with a second rough surface portion having a roughness of 10-point average roughness Rz in the range of 1 μm to 5 μm,
A shield layer having a metal thin film layer having electromagnetic shielding properties is bonded to the second rough surface portion.
A flexible printed circuit board characterized by that. The flexible printed circuit board according to any one of claims 1 to 3,
The substrate main body portion continuous with the terminal portion is provided with a curved portion that is curved in at least one place.
A flexible printed circuit board characterized by that. A flexible printed circuit board having flexibility,
A first insulating layer formed from a liquid crystal polymer that is a thermoplastic resin;
A wiring layer formed on the surface of the first insulating layer and including a plurality of wirings;
A second insulating layer which is disposed so as to cover the wiring layer on the side opposite to the first insulating layer, and is formed of a liquid crystal polymer;
A first adhesive layer that is interposed between the wiring layer and the second insulating layer to bond them, and is filled between the wirings to cover the wiring layer;
A second rough surface portion provided on a surface of the second insulating layer opposite to the wiring layer, and having a ten-point average roughness Rz in a range of 1 μm to 5 μm;
A shield layer having a metal thin film layer that is bonded to the second insulating layer through the second rough surface portion and has an electromagnetic wave shielding property;
A flexible printed circuit board comprising: A method of manufacturing a flexible printed circuit board having flexibility,
Of the single-sided base material in which the metal foil layer is formed on the front side of the first insulating layer formed from a liquid crystal polymer that is a thermoplastic resin, the back surface of the first insulating layer opposite to the metal foil layer A first step of forming a first rough surface portion having a rough surface within a range of 10 μm to 5 μm by performing a roughening treatment on the side;
Before and after the first step, by patterning the metal foil layer, a second step of forming a wiring layer having a plurality of wires and having a desired pattern shape,
A cover lay comprising a second insulating layer formed from a thermoplastic resin and a first adhesive layer laminated on the second insulating layer is positioned on the wiring layer, and the cover lay is heated and pressurized. Then, a third step of bonding the wiring layer and the first adhesive layer while filling the first adhesive layer between the wirings,
A method for producing a flexible printed circuit board, comprising: It is a manufacturing method of the flexible printed circuit board of Claim 6, Comprising:
A reinforcing film comprising a reinforcing layer made of resin and supplementing the thickness of the wiring layer, and a second adhesive layer laminated on the reinforcing layer, is provided at the end of the first rough surface portion of the first insulating layer. A fourth step of adhering the second adhesive layer to the first rough surface portion by heating and pressurizing the reinforcing film in close contact with the portion side;
A method for producing a flexible printed circuit board. It is a manufacturing method of the flexible printed circuit board according to claim 6 or 7,
The second insulating layer is formed from a liquid crystal polymer,
In the first step, the surface of the second insulating layer opposite to the wiring layer is subjected to a roughening treatment, and the ten-point average roughness Rz is in the range of 1 μm to 5 μm. And forming a second rough surface portion having
A shield film provided with a metal thin film layer having electromagnetic wave shielding properties is adhered to the second rough surface portion, the shield film is heated and pressurized, and the shield film is adhered to the second rough surface portion. Comprising a fifth step of forming a layer;
A method for producing a flexible printed circuit board. It is a manufacturing method of the flexible printed circuit board according to any one of claims 6 to 8,
At least a sixth step of forming a curved portion after the heat forming is performed on the flexible printed circuit board before heat forming formed through the third step in a state where at least one portion is curved. Prepare
A method for producing a flexible printed circuit board. A method of manufacturing a flexible printed circuit board having flexibility,
Of a cover lay comprising a second insulating layer formed of a liquid crystal polymer that is a thermoplastic resin as a material and a first adhesive layer laminated on the second insulating layer, the cover lay on the opposite side of the first adhesive layer A first step of subjecting the surface side of the second insulating layer to a roughening treatment to form a second rough surface portion having a roughness of 10-point average roughness Rz in the range of 1 μm to 5 μm;
Before and after the first step, among the single-sided base material in which the metal foil layer is formed on the front side of the first insulating layer formed of the liquid crystal polymer that is a thermoplastic resin, the metal foil layer A second step of forming a wiring layer having a plurality of wirings and having a desired pattern shape by performing patterning;
By positioning the coverlay on the wiring layer and heating and pressing the coverlay, the wiring layer and the first adhesive layer are bonded while filling the first adhesive layer between the wirings. A third step to perform,
A shield film provided with a metal thin film layer having electromagnetic wave shielding properties is adhered to the second rough surface portion, the shield film is heated and pressurized, and the shield film is adhered to the second rough surface portion. A fifth step of forming a layer;
A method for producing a flexible printed circuit board, comprising: