TW201146101A - Flexible circuit board and structure of bend section of flexible circuit board - Google Patents

Abstract

Disclosed is a flexible circuit board which has a bend section subjected to repeated bending and straightening with a small radius of curvature under severe conditions and which yet has durability and excellent flexibility. Specifically, the flexible circuit board is provided with a resin layer and wiring formed of metal foil and has a bend section in at least one portion of the wiring, wherein the metal foil is made of a metal having a face-centered cubic structure, wherein the preferred orientation region, in which the fundamental crystal axis <100> of each unit lattice of the face-centered cubic structure is within 10 DEG of perpendicular to the thickness direction of the metal foil and to a direction along the surface of the foil, occupies an area of 50% or more of the area of the board, and wherein the breaking elongation of the metal foil in a direction tangent to a cross-section (P) of the wiring taken along a plane extending from the ridge line of the bend section in the thickness direction of the metal foil is 3.5% or more and 20% or less.

Description

[Technical Field] The present invention relates to a flexible circuit board having a bent portion and a bent portion structure of a flexible circuit board, and more particularly, A flexible circuit board having durability and flexibility, and a curved portion structure of the flexible circuit board. [Prior Art] A flexible circuit board (flexible printed circuit board) having a resin layer and a wiring made of a metal foil is bendable. Therefore, the movable portion in the hard disk and the hinge portion of the mobile phone are used. The slide sliding portion, the print head of the printer, the optical pickup unit, the movable portion of the notebook PC, and the like are widely used in various electronic and electrical equipment. In recent years, in particular, miniaturization, thinning, and high functionality of such devices have been made, and it has been proposed to fold the flexible circuit board into a small space for storage in a limited space, or to perform various operations such as an electronic device. Flexibility. Therefore, in order to correspond to an operation such as bending with a smaller radius of curvature in the curved portion or frequent repeated bending, it is necessary to improve mechanical properties such as further strength of the flexible circuit board. In other words, it is a resin layer, but the wiring is due to bending or bending with a small radius of curvature, and the strength is poor, which is a bad cause. If it becomes unbearable, it may be damaged in a part of the wiring. It is broken and cannot be utilized as a circuit board. Therefore, for example, in order to reduce the bending stress on the wiring in the hinge portion, a flexible circuit board that is wired so as to be inclined with respect to the rotation axis of the rotation -5 - 201146101 (see Patent Document 1) or toward the hinge portion is formed. A method of reducing the damage of the diameter of the spiral portion caused by the opening and closing operation by reducing the number of turns in the spiral portion having a spiral of one turn or more (see Patent Document 2) has been proposed. However, in these methods, the design of the flexible circuit board is limited. On the other hand, it is obtained by X-ray diffraction of the rolling surface of the rolled copper foil (X-ray diffraction in the thickness direction of the copper foil). The strength of the (200) plane (I), the intensity (10) of the (200) plane obtained by the X-ray diffraction of the fine powder copper is 1/1 〇&gt; It is proposed (refer to Patent Documents 3 and 4). That is, the more the cube orientation of the recrystallized assembly belonging to copper is developed, the more the bendability of the copper foil is improved. Therefore, the above-mentioned parameters (Ι/Ιο) are used to define the degree of development of the cube assembly as flexibility. A copper foil of a wiring material of a circuit board is known. Further, the rolled copper alloy foil obtained by calcining and recrystallizing the element in a concentration in the range of solid solution in the range of copper, such as Fe, Ni, or Ag, under predetermined conditions, causes shear deformation along the slip surface. A report has been proposed which is easy and has good flexibility (refer to Patent Document 5). In addition, in the case of using a copper foil containing impurities such as oxygen or silver, the flexible circuit board which is required to have a high bending property is a copper foil having a purity of about 99% to 99_9% by mass. In the present invention, the purity is expressed by mass concentration unless otherwise specified. In addition, in the test level, there are examples of pure copper having a purity of about 9.5% or oxygen-free copper containing no oxide, which is used as a conductor for a wide range of wires (refer to 201146101, Document 3 '4). ). The impure substance of refined copper contains hundreds of ppm of impurities as copper oxide, silver, iron, sulfur, phosphorus, and the like. Often the purity is 99.96~99.995°/. The copper on the left and right, greatly reduces the oxygen to the next copper. It has been reported in the above-mentioned Patent Documents 3 and 4 that the bending fatigue property of the copper foil which is not produced is superior to that of the fine copper foil, and depends on the copper oxide. Among them, if the purity of the copper is further increased, impurities such as phosphorus and sulfur are required. [PRIOR ART DOCUMENT] [Patent Document 1] [Patent Document 1] JP-A-2002-171033 (Patent Document 2) Japanese Laid-Open Patent Publication No. 2002-300247 (Patent Document 3) [Patent 4] Japanese Patent Publication No. 2003-107036 (Patent Document 5) [Problem to be Solved by the Invention] According to the above situation, the inventor In order to obtain a circuit board design that does not cause any restriction on the design of the circuit board, and to provide a flexible circuit board with durability, it is found to be highly aligned and larger by use. The metal foil having a face-centered cubic lattice crystal structure has a flexible circuit substrate with excellent durability or flexibility. Therefore, the object of the present invention is to provide a highly durable oxygen (mostly anaerobic) Copper pass 1 0 ppm Made of oxy-copper with or without the need to remove silver in the flexibility or curvature of the semi-' carefully broken elongation, can be obtained by bending the invention. Flexible electric 201146101 road substrate, especially Provided that the durability is excellent and the flexibility is good even when the use condition such as the hinge portion or the sliding sliding portion of the mobile phone or the small electronic device is too severe, such as a repetitive curvature having a small radius of curvature. Further, another object of the present invention is to provide durability to an excessively severe condition in a reverse curved portion having a small curvature radius, such as a hinge portion or a sliding sliding portion of a mobile phone or a small electronic device. The curved portion structure of the flexible circuit board having a good curvature of the circumstance. [Means for Solving the Problems] The present invention has been made in order to solve the problems of the above-described conventional techniques, and the following configuration is essential. A flexible circuit board comprising a resin layer and a wiring formed of a metal foil, and a flexible circuit board having a bent portion at least one portion of the wiring, wherein the metal foil has The surface-cube structure of the metal, and the basic crystal axis of the unit cell of the face-centered cubic structure &lt; 1 00 &gt; relative to the thickness of the metal foil The direction and the two orthogonal axes existing in one direction in the foil surface, the priority alignment fields within 1 〇° of the azimuth difference occupy more than 50% of the area ratio, and the ridge line in the curved portion faces the metal The elongation at break of the metal foil in the normal direction of the cross section P of the wiring which is cut in the thickness direction of the foil is 3.5% or more and 20% or less. (2) The flexible circuit board of (1), wherein the metal foil The flexible circuit board of the item (1) or (2), wherein the metal foil is a copper foil and is viewed from the normal direction of the foil surface. The crystal grain size is 25 μπι or more. (4) The flexible circuit board of any one of (1) to (3) wherein the thickness of the metal foil is 5 μm or more and 18 μm or less. (5) The flexible circuit board of any one of (1) to (4) wherein the cross-section of the wiring is rotated from (100) to (110) with [001] as a ribbon axis Any face included in the range from (20 1 0) to (1 20 0) in the direction forms the principal orientation. (6) The flexible circuit board of item (5), wherein the cross-section of the wiring is in a solid triangle of the (100) standard projection image, and is located at a point and representation (1 1 0) indicating (20 1 0 ) ) Any point on the line segment to which the point is connected. (7) The flexible circuit board according to any one of (1) to (6) wherein the wiring is formed in a direction orthogonal to a ridge line in the opposite curved portion. (8) The flexible circuit board according to any one of (1) to (7) wherein the resin layer is composed of polyimide. The flexible circuit substrate of any one of (1) to (8), wherein any one selected from the group consisting of sliding bending, bending bending, hinge bending, and slip bending is formed. The method of repeating the bending portion of the action is used. (10) An electronic device comprising: the flexible circuit board according to any one of the above (1) to (9). -9 - 201146101 (11) A bent portion structure of a flexible circuit board, a resin layer and a wiring formed of a metal foil, and a bent portion of the flexible circuit board used for the bent portion in the wiring The metal foil is a basic crystal axis of a unit cell of a heart-cubic structure composed of a metal having a face-centered cubic structure, a thickness direction of the phase, and a direction existing in the foil surface. The area of the preferential alignment in which the two orientations are within 1 〇° is more than the area ratio, and the elongation of the metal foil in the normal direction of the cross section P of the wiring which is thicker than the ridge line in the curved portion is larger than 20% or less. [Effect of the Invention] According to the present invention, the metal foil constituting the wiring when the flexible circuit board is bent is less likely to cause metal fatigue and has excellent durability against stress. Therefore, it is possible to provide a flexible electric circuit which is excellent in flexibility even if it does not have any restriction on the surface of the flexible circuit board, and which is capable of withstanding flexural bending or curvature, and can realize a thin mobile phone. An electronic device with high durability, such as a thin display, a hard disk, and a DVD device. [Embodiment] The wiring provided in the flexible circuit board of the present invention has a metal structure composed of a metal having a crystal structure of a face-centered cubic lattice system, and has a structure of a single portion, and is orthogonal to the metal foil. The shaft, which occupies 50% of the length of the section, has a length of 3.5%. The radius of the curved part and the design of the deformed tool are smaller than the road substrate, and the printer is formed by having a foil of -10- 201146101. For a metal having a crystal structure of a face-centered cubic lattice system, for example, copper, aluminum, nickel, silver, rhodium, palladium, platinum, gold, or the like is known, and these may be any, but based on the metal foil. Copper, aluminum, and nickel are suitable for use, and copper foil which is mainly used as a wiring of a flexible circuit board is most common. The present invention provides a flexible circuit board excellent in bending durability or flexibility, and in particular, a flexible circuit board having excellent fatigue characteristics in a high deformation range such as a curvature radius of 2 mm or less. In order to achieve the object, in the present invention, even if i) the metal foil is highly aligned, and ii) in the bent portion, the metal foil has a large elongation at break in the principal stress direction, and is not formed as in the present invention. A flexible circuit board which is resistant to fatigue damage at the time of high bending as shown in the invention. That is, by satisfying both of i) and ii) at the same time, it is possible to obtain a flexible circuit board which is resistant to fatigue damage at the time of bending. Specifically, it is necessary that the basic crystal axis of the unit cell of the '· i ) face-centered cubic structure &lt; 1 〇〇&gt; is orthogonal to the thickness direction of the metal foil and the two directions existing in the foil surface. The priority alignment field of the axis 'with a difference of 10° in the azimuth difference is 5 〇°/in area ratio. The above-mentioned 'and' i i ) is a fracture elongation of the metal foil in the normal direction of the cross section P of the wiring which is cut in the thickness direction of the metal foil by the ridge line in the curved portion of 3 · 5 % or more and 20 % or less. When the metal foil is a polycrystalline body as seen in a general electrolytic foil or a rolled foil, 'high elongation at break can be obtained, but the high deformation fatigue obtained in the present invention does not become a high fatigue property. Circuit board. On the other hand, if the aggregate structure is developed and the degree of alignment is large, and the elongation at break is small, the flexible -11 - 201146101 circuit board having the characteristics of the present invention cannot be obtained in the same manner. The present invention is for the first time to understand that the elongation at break of a flexible circuit substrate foil which is high in bending properties is considered to be an important factor in the case where the aggregate structure is developed and the alignment is large. The metal foil may be either a calendered foil or an electrolytic foil, but is preferably a rolled foil in terms of orientation. In the case of a face-centered cubic metal, the member and the heat treatment conditions are designed, whereby a metal foil having a height-group assembly structure having a &lt;1〇〇&gt; main orientation in the normal direction of the box surface can be produced. It is not limited to the use of the flexible circuit board, and the mechanical property of the strong cubic metal foil is characterized by an anisotropic elongation at break elongation, which is very small when stretching in the direction of &lt;1 0 0 &gt; In other words, the more the degree of alignment, and the smaller the thickness of the metal foil, the smaller the elongation at break when the tensile test is performed in the direction of 1 〇〇&gt;. The basic crystal axis of the unit lattice of the surface structure &lt;1 〇〇&gt;, two orthogonal axes with respect to the metality direction (the normal direction of the foil surface) and one of the directions existing in the foil surface is a rolling direction) Each of the azimuth differences is 1〇°, and the area of the first alignment is 95% or more in area ratio, and when the thickness is the general rolled copper foil (hereinafter, for convenience, it is known as rolled copper foil), in the bent portion The elongation at break in the direction of the principal stress reaches 3.5%. The term "elongation at break" as used herein refers to the use of a test piece having a width greater than the thickness of the metal foil, typically a width of 5 to 15 mm, to a relative length of 10%/min. Stretching until breaking at the time of the tensile test. In the present invention, the gold in the metal of the system is highly oriented with the rolling direction extending in the direction of the orientation. Broken cockroaches. , the thickness direction of the cube-shaped foil (the excellent 18 μm in the inside is considered to be "the length of the length is not sufficient to enter the index -12-201146101" by the measurement method shown in the following examples. After the elongation and elongation of the metal foil are laminated with the resin layer to obtain a flexible circuit board, if the rolled copper foil is rolled, the direction of the recrystallization of the recrystallized structure, that is, the longitudinal direction of the metal foil becomes &lt;100&gt; In the general flexible circuit board, 'the long side direction of the circuit is the same as the long side direction of the copper foil in terms of improving the yield when the substrate is taken out. Therefore, the length of the circuit is long. In the general use form in which the side direction is bent, since the principal stress direction coincides with the &lt;1〇〇&gt; direction, the conventional rolled copper foil does not have high fatigue characteristics for the reverse bending. In the method of improving the fatigue characteristics of the flexible circuit board used in the orientation relationship as described above, in the present invention, the purity of the metal foil to be used is improved, and the high-bending use known to date is used. Used In the flexible circuit board, a copper foil containing an impurity such as oxygen or silver, which is intentionally or unavoidably used, is used, for example, as shown in Patent Document 5, it is easier to perform shear deformation along the slip surface, or The purpose of suppressing the increase in resistance is. However, these impurity elements reduce the energy of the laminated defect. The present inventors focused on this point, that is, if the energy of the laminated defect is lowered, the dislocation is easily expanded, and cross slip is less likely to occur. In particular, in the case of stretching in the &lt;100&gt; direction, stretching is less likely to occur. Therefore, in the present invention, a metal foil which exhibits a predetermined preferential alignment described below and preferably has a purity of 99.99% or more is used. (It is more suitable as a copper foil), whereby the elongation at break in the &lt;100&gt; direction can be increased to 3.5% or more, and as a result, the fatigue characteristics when the reverse deformation is applied in the high deformation field are improved. The purity of the metal foil is high. It is advisable, but it is most suitable for the use of 99.999% or 99.9999% from the point of view of manufacturing cost-13-201146101. In addition, even for copper foil with a purity lower than 99.999%, the oxygen concentration is lower. Oxygen copper In the following examples, although narrow, the one of the basic crystal axes &lt;00&gt; of the face-centered cubic structure, such as the [00 1] axis, is the thickness of the opposite metal foil, depending on the conditions of the rolling and the heat treatment. When the direction (the normal direction of the foil surface) is 98% or more and 99.8% or less in the range of 10° or less in the azimuth difference, there is a field in which the elongation at break is 3.5% or more, and the bending fatigue resistance is good. Although it is not clear at the present point, in the oxygen-free copper foil obtained by heat treatment to obtain a predetermined aggregate structure, it is presumed that there is an appropriate size, and the rolling direction which is dispersed relative to the volume ratio is &lt; 2 1 2 &gt; azimuth recrystallizes the residual structure, and increases the elongation at break in the &lt; 1 〇〇&gt; direction. In the flexible circuit board of the present invention, the three-dimensional crystal orientation of the metal foil is defined for the sample coordinate system of the metal foil constituting the circuit, and the aggregated degree of the aggregate structure is in the following range. That is, one of the basic crystal axes of the face-centered cubic structure &lt;1 〇〇&gt;, for example, the [001] axis, is used in the thickness direction of the opposite metal foil (the normal direction of the foil surface) at a distance of 10° in the azimuth difference. The area within the area is preferably 50% or more, preferably 75% or more, and more preferably 98% or more, and is in a horizontally oriented foil surface on the surface of the metal foil. The crystal axis, for example, the [00] axis is a preferred alignment of 50% or more, preferably 85% or more, and more preferably 99% or more in the area ratio of 1 〇°. In the present invention, the accumulation degree of the aggregate structure as described above may be at least in the curved portion, but if it is a metal foil which is more suitable for being laminated on the resin layer, the accumulation degree as described above in the above -14-201146101 The so-called single crystal-like metal foil is not restricted in wiring design. Here, since the crystal orientation of the center located in the preferential alignment is referred to as the main orientation of the aggregate structure, the metal used in the present invention may be referred to as the main orientation of the metal foil in the thickness direction of &lt;1〇〇&gt; Further, the foil surface of the metal foil has a main orientation of &lt;100&gt;. The priority of the preferential alignment of the collective organization, that is, the index indicating the degree of alignment or the degree of accumulation, may be based on the diffraction intensity of the X-ray and the statistical data of the local three-dimensional orientation data obtained by the diffraction of the electron beam. Indicators of objective data. For example, when the metal foil is a copper foil, the intensity (I) from (002) perpendicular to the axis of the crystal ribbon obtained by X-ray diffraction (here, according to the general marking method in the X-ray diffraction) The strength of the (200) plane is preferably a copper foil having a strength (IQ) of (200) plane obtained by X-ray diffraction of fine powder copper, and forming a wiring having a predetermined pattern. The preferred I/U range is 33 to 150, more preferably 50 to 150. Here, the parameter I/Io indicates an orientation degree of the crystal ribbon axis of (1〇〇) and (1 10), that is, the common axis [001], and represents an objective index of the degree of development of the cube assembly. Next, when the metal foil is a rolled copper foil, it is strongly processed at a rolling ratio of a certain value or more, and then heated to recrystallize, the rolled foil surface is set to (〇〇1) main orientation, and the foil surface is The orientation of the recrystallized cube with the rolling direction set to (100) main orientation is developed. The more the cube orientation of the recrystallized assembly belonging to copper is, the more the bending fatigue life of the copper foil is improved. In the flexible circuit board of the present invention, if the I/Iq is less than 25, the increase in the bending fatigue life of the wiring is not sufficiently satisfactory. If the I/U is 33 -15 to 201146101 or more, the increase in the bending fatigue life is changed. It is more obvious. Here, the X-ray diffraction in the thickness direction of the copper foil refers to the alignment in the surface of the copper foil (in the case of a rolled copper foil, the rolling surface), and the strength (I) of the (200) surface indicates The intensity integral ( of the (200) plane obtained by X-ray diffraction. In addition, the strength (1 〇) indicates the intensity integral 値 of the (200) plane of the fine powder copper (the copper powder test material of the Kanto Chemical Co., Ltd. grade I, 325 mesh). In order to obtain an I/U of 25 or more, it is only necessary to obtain a recrystallized structure of the copper foil, and the means is not particularly limited, but the type of the metal foil to be subjected to the intermediate burning condition or the cold rolling processing rate is used. Or the concentration of the impurity is optimized, whereby a rolled aggregate having a large crystal grain size and a rolled copper foil of 1/1 〇 225 can be obtained. Further, for example, after the copper layer is laminated on the resin layer and the rolled copper foil, the copper foil may be heated at a temperature of 300 to 360 ° C for a load of 5 minutes or more. A recrystallized assembly of copper foil was obtained. Further, in order to specify the collective organization in terms of the degree of integration of the three dimensions, it is also possible to specify the area ratio of the priority alignment field within 1 相对 ° with respect to the main orientation of the collective organization. In other words, the crystal surface of the predetermined surface of the metal foil may be, for example, an electron beam diffraction method such as an EBSP (Electrical Back Scattering Pattern) method or an ECP (Electron Channel Pattern Method) or an X-ray such as a Micro Laue method. Confirm by the diffraction method or the like. The EBSP method analyzes crystals based on a diffraction image called a pseudo-Kikuchi line, which is diffracted by each crystal plane generated when a convergent electron beam is irradiated onto the surface of the sample to be measured, and is determined based on the orientation data and the measurement. The position information of the point to measure the crystal orientation distribution of the measurement object is compared with the X-ray diffraction method, and the crystal orientation of the aggregate structure in the micro (micro) domain can be analyzed. For example, the crystal orientations can be specified in each of the microscopic fields, and the maps can be mapped together, and the inclination (azimuth difference) of the plane orientation between the map points is equal to or less than the same color. The distribution of the fields (crystal grains) of the same plane orientation is revealed, whereby the orientation map image can be obtained. Further, the orientation plane having an orientation within a predetermined angle with respect to a specific plane orientation may be included, and the orientation may be defined, and the ratio of the existence of each plane orientation may be extracted by the area ratio. In the EBSP method, in order to exhibit an area ratio of a region within a certain angle from a specific orientation, it is necessary to at least be larger than the field of circuit bending in the flexible circuit substrate of the present invention in order to exhibit an area ratio. The electronic wire is scanned in detail in a manner that is sufficient to obtain a sufficient number of points. However, in the metal foil to be used in the present invention, the size of the circuit to be used is considered, and in the field of 0.005 mm 2 or more, If the average area ratio is to be displayed, it is sufficient to measure 1 000 points or more. However, the present invention differs from the inventions described in Patent Documents 3 and 4 in that the orientation of the invention of the patent documents is defined only by the normal direction of the box measured by the X-ray. In contrast, the present invention is defined by a third dimension. In order to obtain high fatigue characteristics for bending, it is particularly important to make the main deformation, the principal stress direction, that is, the &lt;1 〇〇 &gt; accumulation degree in the foil surface when bending. Further, in the present invention, the size of the recrystallized grains, that is, the crystal grains having a cubic orientation is preferably 2 5 μm or more in terms of an average enthalpy. Further, in the case of the present invention, in particular, when high flexibility is required, the metal foil forming the flexible -17-201146101 circuit board may be a rolled copper foil having a thickness of 5 to 18 μm, preferably a calender having a thickness of 9 to 12 μm. Copper foil. When the rolled copper foil is thicker than 18 μm, it is difficult to obtain a flexible circuit board having excellent fatigue characteristics in a high-deformation field having a radius of curvature of 2 mm or less. Further, when the thickness is thinner than 5 μm, it is difficult to laminate the metal foil and the resin layer, and it is difficult to form a homogeneous flexible circuit board. Different from the first method for improving the fatigue characteristics of the flexible circuit substrate described above, in the present invention, the second elongation at break of the face-centered cubic metal foil for improving the single crystal close to the height alignment In the case of the method, the <1〇〇> direction in which the elongation at break is small does not become the principal stress direction, and the wiring structure of the flexible circuit board is designed. Specifically, the following method is exemplified. As described in the first aspect, by designing the rolling and recrystallization conditions, it is possible to produce a metal foil having a highly aligned cubic assembly structure having a rolling direction and a normal orientation of the foil surface in the normal direction of the foil surface. Further, in the wiring, the direction in which the circuit is cut is shifted from the rolling direction, that is, the &lt;1〇〇&gt; direction by a predetermined angle, and the circuit is obliquely drawn, whereby the main stress direction can be obtained when the bending is performed. A flexible circuit board having a large elongation at break. By the method as described above, the elongation at break of the metal foil in the normal direction (the principal stress direction in the curved portion) of the cross section of the wiring which is cut in the thickness direction of the metal foil by the ridge line in the curved portion is 3 5% or more 'must make the above-mentioned section Ρ with [001] as the ribbon axis and any principal surface contained in the range of (20 1 0 ) to (1 20 0 ). Here, the relationship between the ribbon axis and the plane orientation is shown in Fig. 1. (20 1 〇) and (1 20 0 ) are in the relationship of -18- 201146101 [00 1] as the common axis, that is, the ribbon axis, located on the axis of [〇〇1] (100) to ( 110) [in the plane of rotation from (100) to (〇1〇)]. That is, when it is displayed on the inverse pole map of the normal direction of the cross section p, the faces of '(001), (20 10), and (110) are as shown in Fig. 2. Based on the symmetry 'on the inverse pole map, 2〇 〇) is expressed at the same position as (20 1 0). The metal of the metal foil in the present invention has a face-centered cubic structure. The crystal axis of the unit cell is [1 〇〇], [010], [001]', but in the present invention, if it is in the thickness direction of the metal foil (vertical direction with respect to the surface of the metal foil), &lt;1〇0&gt When the priority orientation is 'mark the axis as [0 0 1]', the foil surface orientation is marked as (〇〇i ) 'but even if the axis is replaced based on the symmetry of the face-centered cubic structure, it is equivalent. Of course, these are included in the present invention. Then, the main orientation in the foil surface must be 2.9 with respect to the main deformation direction of the curved portion, that is, the cross-sectional normal direction of the wiring (the perpendicular to the wiring cross section P) when the ridge line in the curved portion is cut in the thickness direction. The angle of ~ 87.1 ° [(20 1 0) ~ (1 20 0)] is preferably 5.7. The angle of ~ 84.3 ° [(10 1 0) ~ (1 10 0)] is more preferably 11.4. ~ 78.6 ° [(510) ~ (150)] angle, more preferably 26.6 ° ~ 63.4 ° [(210) ~ (120)] angle, most suitable for 30 ° or 60 ° [(40 23 0) or (23 40 0) is appropriate. Here, the inside of [ ] indicates the plane orientation of the section P corresponding to each angle. Here, the symmetry of the crystal may be described as having a normal line with respect to the wiring cross section P having an angle of 2.9 to 45 with respect to the basic crystal axis &lt;1〇〇 &gt; in the plane of the metal foil. Here, the wiring when the ridge line in the curved portion is cut in the thickness direction is -19-201146101

In the cross-section P, for example, when the flexible circuit board is bent into a U-shape, a ridge line L is formed on the outer side, and the ridge line L is cut toward the thickness direction d of the flexible circuit board. The part of the wiring in the section. In addition, the ridge line L is a vertex phase formed when the flexible circuit board is bent, and the cross section of the flexible circuit board is viewed along the bending direction (the thick black arrow in FIG. 3). Linked line. Here, for example, a case where the ridgeline L such as a sliding curve to be described later moves on the flexible circuit board is also included. In addition, in the third figure, the resin layer 1 is outside and the wiring 2 is bent inward (the side in which the circle having the radius of curvature is inscribed is inside), but the wiring 2 may be folded outward. The curved mode is self-evident in various applications. When subjected to a forced displacement of a certain curvature, the metal foil is mainly subjected to tensile or compressive stress. Which part of the flexible circuit board subjected to bending is subjected to stretching or compression depending on the composition of the metal foil and the resin, but is more than the neutral axis (or neutral surface) of stretching and compression. The farthest portion of the outer side of the bay ridge is too severe due to metal damage, and it is generally seen that the tensile stress in the normal direction of the cross section of the wiring when the ridge line in the curved portion is cut in the thickness direction becomes the principal stress. That is, the principal stress direction of the wiring in the bent portion is in the direction indicated by the arrow 21 in Fig. 3, and typically, the wiring profile P which is cut toward the thickness direction of the metal foil with respect to the ridge line of the curved portion. The normal directions are equal, and intersect perpendicularly to the [〇〇1] axis that is aligned toward the thickness direction of the metal foil. Considering the mechanical properties of the metal foil in the flexible circuit board, the metal foil is simply stretched toward the direction of the principal stress shown by the arrow 21 in Fig. 3 - 201146101 It is an important characteristic that the stress-deformation characteristic is 20 when the time is 11 o'clock. Here, as shown in the examples of FIGS. 4I and (d), it is assumed that the [100] axis of the metal foil having the crystal structure having a face-centered cubic shape is curved so as to be orthogonal to each other. The cross section of the wiring which is cut in the thick direction of the flexible circuit board by the ridge line of the curved portion is a (100) plane, but the cross section P of the wiring when the ridge line in the curved line is cut in the thickness direction is as shown in FIG. It is shown that [001] is the ribbon axis and any surface included in the range of (20 1 0) to (1 200) (the two arrows in the figure) in the rotation of (100) to (010) is presented as the main Orientation, which can increase the elongation at break. In the first drawing, the range of (20 1 0) to (1 20 0) is shown, but there is a surface equivalent to the surface included in the range in the face-centered cubic crystal structure. Therefore, the equivalent faces of the cross section of the wiring and the range of (2 0 1 0 ) to (1 〇) are different from each other, and are included in the present invention. In the second method, the cross section P of the wiring cut by the ridge line in the curved portion in the thickness direction has a main orientation between the (20 1 〇) to (1 20 0 ) and is preferentially aligned, thereby breaking elongation The reason for the improvement is that in the metal having a face-centered cubic structure when the tensile stress is applied to the normal direction of the section P, that is, the principal stress direction, among the eight {i} belonging to the slip surface, The German factor has the largest main slip surface to be 4 faces, so the shearing and sliding becomes good, and local work hardening is not easy to occur. In general rolled copper foil, the long side direction of the metal foil is generally equivalent to the pressing direction, as in the first 4 (c) or (d), the circuit is formed along its main orientation &lt;1〇〇. For example, the embodiment of Patent Document 5 corresponds to the form of Fig. 4 &lt;-21 - 201146101). As described above, when the cross-sectional orientation of the wiring at the time of the cut in the curved portion is (1 〇〇), the Schmid factor of the eight slip surfaces becomes equivalent and the function is 8, and the dislocation is easily accumulated locally. . According to the above difference, the general use form of the circuit in which the flexible circuit board of the second method is bent in the longitudinal direction is compared with the main deformation direction of the most curved portion in the cross section P in the flexible circuit board. That is, the normal direction of the cross section of the wiring when the direction of the curved portion is cut is 30°. In order to make the stress direction and the tensile orientation of the tension equal to or higher than the mechanism, the cross section of the wiring at least when the ridge line in the curved portion is formed P has [?1] as a ribbon axis, and a specific orientation between 20 0) has a main orientation and has ί, that is, the second aspect of the present invention is made of a metal foil, and the thickness direction of the metal foil has &lt; The main foil of the main foil of 1〇〇&gt; has a main orientation of &lt;100&gt;, and the middle ridge line is cut between the cross-sections of the wiring (20 1 0) to (1 20 0 ) when the thickness is cut in the thickness direction. Wiring such as specific orientation priority alignment. At this time, the method of the profile Ρ preferentially aligns the specific direction between (10 1 0 ) and (1 10 0 ), and more preferably has the main orientation at (5 1 0 ) to (1 1 〇) for preferential alignment. More preferably, the priority orientation is given in the specific orientation of the 21 directions, and the central orientation is in the vicinity of (40 2 3 0), and the priority ridge line is oriented in the thickness direction, and the sliding system is simultaneously displayed when the bending is performed. The bending resistance characteristics of the prior art are superior. The ridge line in the ideal orientation system is facing thickness or 60°, but this is the reason. When considering the incision in the thickness direction (20 1 0 ) to (1 g first It can be aligned. It has a face-centered cubic orientation, and the metal has a specific orientation between the normal direction of the curved portion ip and the main orientation, and the linear orientation is preferably the position with the main orientation 〇) to (no The most suitable one is the metal foil which is preferentially aligned if the foil surface is -22-201146101 (00 1 ), for example, [001] and [100] in the foil surface are equivalent. In the flexible circuit board of the present invention, the ridge line in the curved portion faces the thickness The main orientation of the cross section p of the wiring at the time of cutting may also be described as a specific orientation between (1 2 0 0 ) and (11 0 ), and preferably has a main orientation in a specific orientation between (120) and (110). For the preferred alignment, it is most suitable to be described as having a main orientation in the vicinity of (23 40 0) for preferential alignment. Further, the thickness direction of the metal foil has a main orientation of &lt;1〇〇&gt;, and the metal The main surface of the foil has a main orientation of &lt;1〇〇&gt;, and the cross section P of the wiring when the ridge line in the curved portion is cut in the thickness direction is specific between (20 1 0) to (1 20 0). The orientation has a main orientation, and may be referred to as a cross section of the wiring when the ridge line in the curved portion is cut in the thickness direction when the reverse triangle is indicated on the stereo triangle of the (100) standard projection map of FIG. The orientation is any plane on the line segment connecting the point indicating (2 0 1 0 ) and the point indicating (1 1 〇). In addition, the flexible circuit substrate in the second method is made of the thickness direction of the metal foil. Wiring is formed for the material of the (2) axis of the [〇〇1] axis. The normal line of the cross section of the wiring when the ridge line in the curved portion is cut in the thickness direction has an angle of 2.9 to 8 7. 与 between the axis of the foil surface. The second method of the present invention is characterized in that the elongation at break of the metal foil in the direction of the principal stress in the curved portion is formed to be 3.5% or more, and the reverse deformation such as having a radius of curvature of 2 mm or less is less likely to occur, or even stress is not easily obtained. A flexible circuit board having high metal fatigue and high flexibility. Further, in the present invention, by combining the first method and the second method -23-201146101, it is possible to obtain metal fatigue characteristics more reliably. The bending circuit base plate has a fracture elongation of the metal foil in the direction of the principal stress, preferably 4% or more, more preferably 9% or more. The upper limit of the elongation is 100&gt; of the unit cell of the face-centered cubic structure, and the thickness direction of the metal foil (the normal of the foil surface is in a certain direction in the foil surface (the one is the rolling direction). The priority alignment field within the range of 18 μm is within the range of the present invention, and may be specified as 20% or less, but if the basic crystal axis of copper is &lt;1 00 &gt; The two orthogonal axes in a certain direction in the thickness direction have an azimuth difference of 1G. The area of the alignment is 95% or more in area ratio, and in the case of a thicker shape, the upper limit of the elongation at break is 15% or less | The type of the resin of the resin layer of the flexible circuit board is not particularly limited, and may be exemplified by a user in a general substrate, and examples thereof include polyimine, liquid crystal polymer, polyphenylene sulfide, and polyether ether ketone. Etc., which exhibits good flexibility when it is a circuit board, and is suitable for heat-resistant polyimide or liquid crystal polymer. The thickness of the resin layer can be appropriately set according to a flexible circuit board or the like, but flexibility From the point of view, the range is better, preferably in the range of 9 to 50 μηι, and preferably in the range of 10. If the thickness of the resin layer is less than 5 μηη, there is an insulating crucible, and conversely, if it exceeds 75 μm, when loaded in a small size The flexibility of good mechanical properties can be formed in 3.5%, with respect to the fracture basic crystal axis &lt; direction) and the presence of 2 orthogonal axes, the ratio is 50%, and the unit lattice of the calendered foil The flexible layer having a priority of 1 μm or less on the surface of the foil is 12 μm or less, and the flexible circuit forming the resin is also excellent in the properties of the polyimide and the polyester. Therefore, the use and shape are 5 to 75 μm. When the range of 30 μm η reliability is reduced, there is a case where the thickness of the entire circuit board of the -24-201146101 becomes too thick, and the bendability is also lowered. In addition, when the flexible circuit board is applied to a mobile phone, In the case of sliding a sliding portion or the like, a cover member made of a cover film or the like is bonded to a wiring formed of a metal foil, and in this case, it is considered to be applied to the wiring. Balance of stress to design The composition of the cover material and the resin layer is preferred. According to the knowledge of the inventors of the present invention, for example, a polyimine having a tensile modulus of 4 to 6 GPa at 25 ° C and a thickness of 14 to 17 μm as a resin layer having a thickness of 8 to 17 μm is exemplified. a cover film composed of a thermosetting resin and a polyimide film having a thickness of 7 to 13 μm, and a cover film having a tensile modulus of 2 to 4 GPa of the entire adhesive layer and the polyimide layer. As a structural example of the covering material, or a polyimide having a tensile modulus of 6 to 8 GPa at 25 ° C and a thickness of 12 to 15 μm as a resin layer, it has thermosetting property of 8 to 17 μm in thickness. Two layers of the adhesive layer composed of a resin and a polyimide layer having a thickness of 7 to 13 μm and a coating film having a tensile modulus of 2 to 4 GPa of the entire adhesive layer and the polyimide layer as a covering material. Examples. Regarding the means for laminating the resin layer and the metal case, for example, when the resin layer is composed of polyimide, the metal foil can be laminated on the polyimide film or the thermoplastic polyimide. Combination (so-called stacking). For the polyimide film to be used in the stacking method, for example, "Kapton" (Toray DuPont Co., Ltd.), "Apical" (Kaneka Chemical Industry Co., Ltd.), "Upi lex" (Ube) Xingye Co., Ltd.) and so on. When the polyimide film is heated and pressure-bonded to the metal foil, the thermoplastic thermoplastic polyimide resin is shown to be in the range of -25 to 201146101. Further, from the viewpoint of easy control of the thickness of the resin layer, the bending property, and the like, the polyimide film may be dried and hardened after the metal foil is coated with the polyimide precursor solution (also referred to as a polyamic acid solution). And the layered body (so-called casting method). The resin layer may be formed by laminating a plurality of resins, or may be formed by laminating two or more kinds of polyimine layers having different linear expansion coefficients, etc., but it is preferably from the viewpoint of ensuring heat resistance or flexibility at this time. In order to prevent the epoxy resin or the like from being used as an adhesive, it is preferable that all of the resin layers are substantially formed of polyimide. In the case of a case consisting of a single polyimine and a case of a plurality of polyimine, the tensile modulus of the resin layer is preferably 4 to 10 GPa, preferably 5 to 8 GPa. In the flexible circuit board of the present invention, the linear expansion coefficient of the resin layer is preferably in the range of 10 to 30 ppm/°C. When the resin layer is composed of a plurality of resins, the coefficient of linear expansion of the entire resin layer may be within this range. In order to satisfy the conditions as described above, for example, a low linear expansion polyimine layer having a linear expansion coefficient of 25 ppm TC or less, preferably 5 to 20 ppm/° C., and a coefficient of linear expansion of 26 ppm/° C. or more are used. The resin layer composed of a highly linear expandable polyimide layer of preferably 30 to 80 ppm/° C. can be formed to have a thickness ratio of 10 to 30 ppm/° C. by adjusting the thickness ratio. The ratio of the thickness of the preferred low-expansion polyimine layer to the high-expandable polyimine layer is 70: 30 to 95:5. Further, the low-line expandable polyimide layer is a main resin layer of the resin layer, and the high-expansion polyimine layer is preferably provided in contact with the metal foil. Among them, the coefficient of linear expansion is a sample obtained by using a polyamidimide in which the ruthenium imidization reaction is sufficiently completed, and is heated at a temperature of -26-201146101 to 250 ° C using a thermomechanical analyzer (TMA) at 10 ° C / min. The speed cooling can be obtained from the average linear expansion coefficient in the range of 240 to 100 t. Further, the flexible circuit board of the present invention includes a resin layer and a wiring formed of a metal foil, and has a bent portion for any user. That is, the movable part in the hard disk, the hinge part or the sliding sliding part of the mobile phone, the printing head of the printer, the optical pickup part, the movable part of the notebook type PC, etc. Electrical equipment and the like are widely used, and the circuit board itself is bent, twisted, or deformed in accordance with the operation of the loaded machine, and a bent portion is formed in any of them. In particular, since the flexible circuit board of the present invention has a curved portion structure excellent in bending durability, it is suitable for frequent bending with repeated operations such as sliding bending, bending bending, hinge bending, and slip bending, or Corresponding to the miniaturization of the loaded machine, the radius of curvature is 0.38 to 2.0 mm for the bending action, 1.25 to 2_0 mm for the sliding bending, 3.0 to 5.0 mm for the hinge bending, and 0.3 to 5.0 mm for the slip bending. In the case of strict use conditions such as 2.0 mm, it is particularly effective in the use of a narrow gap of 0.3 to 1 mm and a strict slippage requirement for bending performance. Regarding the manufacturing method of the flexible circuit board in the present invention, i) obtains a calendering of a cubic assembly structure which exhibits a normal alignment of the axis toward the foil surface (a perpendicular to the surface of the metal foil). The composite in which the metal foil and the resin layer are bonded to the foil surface of the metal foil is opposite to the normal direction of the cross section of the wiring when the design is bent in the direction of the principal stress, that is, the ridge line in the curved portion is cut in the thickness direction. The main orientation of the [1 〇〇] in the metal foil surface has a ridge angle of 2.9° to 87. The angle of the ridge is formed -27-201146101, or ii) the metal foil constituting the wiring is formed to have a purity of 99.999. % or more, or iii) may use the methods of i) and ii) at the same time. At this time, the metal foil does not necessarily have to present the cubic aggregate structure from the beginning, and the cubic aggregate structure can also be formed by heat treatment, for example, in the manufacturing process of the flexible circuit substrate, specifically, in the formation of the resin layer. Heat treatment is performed to form a cube assembly. That is, by performing the heat treatment, the basic crystal axis of the unit cell is &lt;1 〇〇&gt; in such a manner that the area occupied by the &lt;1 〇〇> axis within 10° of the azimuth difference is more than 50%. The direction of the thickness of the metal foil is preferentially aligned, and the basic crystal axis is &lt;1 〇〇&gt; in such a manner that the area occupied by the &lt;100 &gt; axis within 10 degrees of the azimuth difference is 50% or more. The other surface of the metal foil may be preferentially aligned in the horizontal direction. The recrystallized aggregate structure of the rolled copper foil has a general calender plane orientation of {100} and a calendering direction of &lt;100&gt;. Therefore, the (001) main orientation is formed in terms of the rolling surface orientation. In addition, when a metal foil having a purity of 99.999% or more is used, even if a circuit is formed in any direction for wiring, the elongation at break can be ensured at 5.3 % or more, and a flexible circuit board having a large design range can be formed. In the case where the second method is used, more specifically, as shown in FIG. 3, when, for example, the flexible circuit board is bent into a U shape, the outer side thereof is formed (inscribed with an inscribed circle having a radius of curvature) On the opposite side, the ridge line L is formed, but the ridge line L has an inclination in a range of α=2·9 to 87.1 (°) in a state orthogonal to the [1 〇〇] axis of the metal foil forming the wiring. . An example of the state shown above is shown in (a) and (b) of Fig. 4. Incidentally, (C) and (d) of Fig. 4 are relative to the [100] axis, and the ridge line is in a state of orthogonality of -28-201146101 (α = 0). Here, if α is less than 2 · 9 °, no clear effect is confirmed in the bendability. If α = 1 1 . 4 to 7 8.6 ( ° ), the bending durability of the bent portion structure is further improved. In the present invention, in the case of the above α = 2.9°, the cross section P of the wiring when the ridge line is cut toward the thickness d direction corresponds to the (20 1 0 ) plane, and when α = 45, the profile P Corresponding to the (1 10 ) plane, if α = 87. 1, the profile Ρ is equivalent to (1 20 〇) plane. In addition, in the face-centered cubic structure, [1 〇〇] is equivalent to [0 1 0], so the orthogonal axes and ridges of the foil surface of [100] shown in Fig. 4 (a) and (b) are shown. The angle range of the angle α formed is in accordance with the angle range formed by [100] and the normal line of the section P, and the angle range formed by [1 〇〇] and the ridge line, and the width, shape, pattern, and the like of the wiring are Although it is not particularly limited, it may be appropriately designed according to the use of the flexible circuit board, the mounted electronic device, or the like. However, since the bending structure of the present invention has excellent bending durability, even in the case of adopting the second policy In addition, it is not necessary to perform wiring in a direction orthogonal to the ridge line in the opposite curved portion in order to reduce the bending stress on the wiring, for example, in a direction orthogonal to the slanting line of the hinge portion, that is, Wiring at a minimum minimum distance is required. Fig. 4 (a) and (b) show a flexible circuit board used for, for example, a hinge portion of a mobile phone, and a resin layer 1, a wiring 2 formed of a metal foil, and a terminal 3 of a connector. . In any of Figs. 4(a) and 4(b), the position of the ridge line L in the curved portion is displayed near the center, and the ridge line L has a [100] axis direction with respect to the metal foil forming the wiring 2 (90 + α) ° angle. Here, Fig. 4(a) shows an example in which wiring is formed obliquely in the middle of the connector terminals 3 -29 to 201146101 at both ends and in the vicinity of the ridge line L, but it may be as shown in Fig. 4(b). Wiring is performed between the connector terminals 3 at the shortest distance. In the case where the position of the ridge line L in the curved portion is fixed, the ridge line L in the curved portion such as a slide type mobile phone may be moved to slide and slide as in a folding mobile phone. (The thick arrow direction recorded in Figure 4(b)). In the flexible circuit board of the present invention, the wiring layer made of a metal foil is provided on at least one surface of the resin layer. However, it is also possible to provide a metal foil on both surfaces of the resin layer as needed. As described above, the metal foil which constitutes the wiring in the curved portion when the flexible circuit board is bent is a metal foil which is formed to have a high degree of alignment and is elongated in the principal stress and the main deformation direction. When a high-bending reverse bending having a small bending radius is performed, local stress concentration due to crystal anisotropy is less likely to occur, and two effects such as dislocation accumulation are less likely to occur, and metal fatigue is less likely to occur. Durability against stress and deformation is not restricted by the design of the flexible circuit board, and it has strength that can withstand bending even if it is repeatedly bent or has a small radius of curvature, and has excellent flexibility. Circuit board. [Examples] Hereinafter, the present invention will be more specifically described based on examples and comparative examples. The type of the copper foil used in the examples and the like and the synthesis of the polyaminic acid solution are as follows: [copper foil A] -30- 201146101 A commercially available rolled copper foil having a purity of 99.9% and a thickness of 9 μm. [Copper foil 市] Commercially available electrolytic copper foil, purity 99.9%, thickness 9 μηι. [Copper foil C] Oxygen-free copper foil, purity 99.99%, thickness 9μηι, process conditions Α. Mass ppm oxygen: 2, silver: 18, phosphorus: 2.1, sulfur expansion: 4, iron: 1.5 [copper foil D] refined copper foil, purity 99.999%, thickness 9 μιη, process condition A. Mass ppm oxygen: 2, silver: 5, phosphorus: 〇. 〇 1, sulphur: 0.01, iron 0.002 [copper foil E] refined copper foil, purity 99.9999%, thickness 9 μιη, process condition A. Mass ppm oxygen: &lt;1, silver: 0.18, phosphorus: &lt;〇.〇〇5, sulfur: &lt;0.005, iron: 0.002 [copper foil F] refined copper foil, purity 99.9999%, thickness 9 μm , process conditions β, mass ppm oxygen: &lt;1, silver: 0.18, phosphorus: &lt;〇.〇〇5, sulfur: &lt;0.005, iron: 0.002 -31 - 201146101 [copper foil G] refined copper Foil, purity 99.9999%, thickness 9μιΏ, process condition C. Mass ppm oxygen: &lt;1, silver: 0.18, phosphorus: &lt;0.005, sulfur: &lt;0.005, iron: 0.002 [copper foil 市] Commercially available rolled copper foil, purity 99.9%, thickness 12 μιη. [Method for Producing Copper Foil] Copper foil crucible and copper foil crucible are commercially available leg-stretched copper foil, and copper foil crucible is a commercially available electrolytic copper foil produced by a copper sulfate bath. These copper foils, which are commercially available as high-bend products, have a purity of 99.9%, which is higher in the case of commercial products. The copper foil C to the copper foil G are processed by the inventors of the present invention, and the copper material of a predetermined purity is cast and solidified in a graphite mold, and is subjected to calendering to form a predetermined thickness. The thickness of the ingot is 10 mm, and after the cold rolling is reduced to 1 mm, the copper foil C, the copper foil D, and the copper foil E are subjected to cold pressing after being blunt at 300 ° C for 30 minutes. Extend to 9μπι (process condition A). Further, the copper foil F is subjected to cold rolling ('process condition Β) until the intermediate blunt is performed until 9 μm. Further, the copper foil G is subjected to cold rolling at a temperature of 80 ° C to 80 μm (process condition C) [synthesis of a polyaminic acid solution] -32-201146101 (Synthesis Example 1) A reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen was placed in N,N-dimethylacetamide. In the reaction vessel, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) was stirred while being stirred in a vessel. Next, pyromellitic dianhydride (PMDA) was added. The input was carried out in such a manner that the total amount of monomer input was 1 5 w t%. Thereafter, stirring was continued for 3 hours to obtain a resin solution of polyamic acid a. The resin solution of the polyamic acid a had a solution viscosity of 3,000 cps. (Synthesis Example 2) N,N-dimethylacetamide was placed in a reaction vessel equipped with a thermocouple and a stirrer and capable of introducing nitrogen. 2,2'-Dimethyl-4,4'-diaminobiphenyl (m-TB) was introduced into the reaction vessel. Next, 3,3·,4,4·-biphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (PMDA) were added. The total amount of the monomer input was 15 wt%, and the molar ratio of each acid anhydride (BPDA: PMDA) was 20:80. Thereafter, stirring was continued for 3 hours to obtain a resin solution of poly-proline b. The solution viscosity of the resin solution of the polyaminic acid b was 20,000 cps 0 [Example 1] The above-mentioned prepared polyaminic acid solution a was applied to seven kinds of copper foils of copper foil A to copper foil G to make it Drying (forming a thermoplastic polyimide having a film thickness of 2 μm after hardening), coating the polyphthalic acid b thereon and drying it (curing to form a low thermal expansion polyimine having a film thickness of 9 μm), and additionally Coated with polyfluorene-33- 201146101 Amine acid a and dried (hardened to form a thermoplastic polyimide having a film thickness of 2 μm), and the load is 5 minutes or more based on the integrated time at a temperature of 300 to 3 60 °C. The heating conditions of the type form a polyimine layer composed of a three-layer structure. Next, the length of the copper foil in the rolling direction (MD direction) is 250 mm, and the direction in which the direction perpendicular to the rolling direction (the TD direction) is a rectangular shape having a width of 150 mm is cut out, as shown in FIG. The single-sided copper-clad laminate 4» having the polyimide layer (resin layer) 1 having a thickness of 13 μm and the copper foil 2 having a thickness of 9 μm was subjected to a tensile modulus of 7.5 GPa.

In the single-sided copper-clad laminate 4 obtained as described above, colloidal vermiculite is used for the rolling surface 2a of each of the copper foils A to the copper foils G, and after mechanical and chemical honing, the EBSP apparatus is used. Azimuth resolution. The apparatus used was FE-SEM (S-4100) manufactured by Hitachi, Ltd., EBSP apparatus manufactured by TSL Corporation, and software (ΟIM A n a 1 y s i s 5 · 2 ). The measurement field is in the field of about 800 μm η χ 1 600 μιη, and the acceleration voltage is 20 kV and the measurement interval is 4 μιηι. The evaluation of the orientation is expressed by the ratio of the thickness direction of the foil and the rolling direction of the foil to the measurement point of <1 00 &gt; within 1 〇° with respect to the entire measurement point. The number of measurements was carried out for five different samples of each individual, and the percentage of the decimal point was rounded off. Further, using the obtained data, the crystal grain size was evaluated as a crystal grain boundary when the difference in orientation of adjacent crystal grains was 15 or more, and the average particle diameter was determined for the polycrystalline system. The results are shown in Table 1. -34- 201146101

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Remarks Comparative Example Comparative Example Comparative Example Example Example Comparative Example Elongation at break in the direction of rolling (%) ____ I csi CVJ r - CsJ CO in CO CO 00 CO CO in • ϋΜ Domain Brewing g circle! Tortoise § ο OJ o Inch CSJ ΙΛ r~ r— CO r~ ιο r- r~ 00 r— r- o CsJ r- bending test life, (times) ί I _I 1050 oo LD 1050 I 1500 1800 1400 1000 S Μ m§ &gt;800 &gt;800 I &gt;800 &gt;800 m CM 8 •mm mvt CD σ&gt; (0 r- σ&gt; CD O) (D 0) 〇in in inch 埘Λβ ft8M SV» inch 0) strict in 0) in O l〇O) CO in 00 purity (mass%) _ί σ&gt;σ&gt;σ&gt;σ&gt;σ&gt;σ&gt; 99.99 I 99.999 99.9999 99.9999 99.9999 Variety copper foil A copper foil 铜 copper foil c copper foil D copper ME copper foil F Copper foil G-35-201146101 It is understood that the rolled copper foil other than the copper foil B has a cubic aggregate structure, and the copper foil surface orientation and the rolling direction have a principal orientation of {00 1} &lt; 100 >. This is based on the fact that the calendered copper foil is recrystallized by the heat of the polyimine hardening to form a recrystallized aggregate structure. However, the degree varies depending on the species, and the orientation of the cube orientation with respect to the copper foils A, C, D, and E is extremely high. The orientation of the cube orientation is such that the copper foil having a purity of 99.9% or more does not depend on the purity thereof, and has a large dependence on the processing method of the copper foil. These copper foils are formed in a field of view of 800 x 1600 μm, and the entire field of view is composed of granules having a cubic orientation, and is formed into a structure in which crystal grains of 5 μm or less having different orientations are dispersed in an island shape. The area ratio of the island-like structure is as small as 2% or less, so that the recrystallized grains having the cube orientation have the same orientation and are integrated, and the size of the recrystallized grains is 9 μm in the thickness direction and the foil thickness, in the foil surface. It is 800 μmη or more. Further, since the area ratio of the recrystallized grains having the cubic orientation of the copper foil F and the copper foil G is not high, they exist independently of each other, and the average particle diameter in the foil surface is 25 μm and 20 μm, respectively. On the other hand, the electrolytic copper foil was a polycrystalline body having an average particle diameter of 1 μηη, and almost no alignment property was observed. Next, a predetermined mask is coated on the copper foil 2 side of the single-sided copper-clad laminate 4 obtained above, and is etched using a ferric chloride/copper chloride-based solution, as shown in Fig. 6 (wherein the wiring direction) Η is at an angle of 0° with respect to the MD direction, and the wiring direction Η (Η direction) of the linear wiring 2 having a line width (1) of 150 μm is parallel to the MD direction (&lt;100&gt; axis), and A wiring pattern is formed in such a manner that the space width (s) is 205 μm. Then, the wiring direction along the -36-201146101 circuit board is obtained in accordance with JIS 647 1, and has a width of 150 mm in the longitudinal direction and a width in the direction orthogonal to the direction Η. A 15 mm test flexible plate 5 was used. The MIT bending test was performed using the test flexible circuit board obtained above, ί C5016. The mode diagram of the test is shown in the apparatus. The end of the long side of the flexible circuit board 5 manufactured by Toyo Seiki Co., Ltd. (STROGRAPH-R1) is fixed to the clamp of the bending device, and the other end is fixed by a heavy object. The number of times the conduction of the wiring 2 bent out of the circuit board 5 is blocked by the radish speed of 135 ± 5 degrees at a vibration speed of 150 times/min. As a number. In this test condition, the ridge line formed in the curved portion is curved orthogonally to the wiring direction Η of the wiring 2 of the flexible circuit board 5, so that the principal stress applied to the copper circuit and the main deformation are delayed. Parallel tensile stress and tensile deformation. When the circuit was observed in the thickness direction of the copper foil, it was confirmed that a crack was formed in the vicinity of the curved portion substantially perpendicularly to the rolling direction to form a broken line. The results of the lifespan are shown in Table 1. The bending life of Table 1 is the result of preparing the test flexible circuit board for each copper. The results of Table 1 show that the bending fatigue life depends on the accumulation degree of the aggregate structure, and the same processing. According to the method, the bending fatigue life of the copper foil C, the copper foil D, and the copper foil which are equal in orientation is the same. And wiring circuit base S according to JIS I 7 diagram. The test piece is rotated around the center of the test, and the bending test is applied. After the test is applied, the ridge line is attached to the curved foil. The degree of the cube is also large. -37- 201146101 Next, in order to investigate the dominant factor of the bending life, the tensile test is performed in parallel with the main stress of the bending, the main deformation direction, that is, the rolling direction. In order to investigate the characteristics of the copper foil monomer, the resin layer was dissolved by the single-sided copper-clad laminate 4 before etching, and a tensile test of the copper foil alone was carried out. It was confirmed that the structure of the copper foil did not change during the dissolution of the polyimide. The tensile test was cut into a length of 150 mm in the rolling direction (MD direction) of the copper foil, and cut into a width of 10 mm in the direction perpendicular to the rolling direction in the foil surface, in the longitudinal direction. The measurement was carried out at a distance between the punctuation points l〇〇mm' tensile speed l〇mm/min. In the measurement, seven samples were prepared for each type of copper foil, and the fracture stress (breaking strength) obtained by the measurement and the average enthalpy of the elongation at break were shown in Table 1. As a result, in the copper foil in which the aggregate structure was developed, it was found that the fracture strength was not related to the fracture strength, but the elongation at break was correlated with the bending fatigue life. Further, the copper foil B has a large strength and a large elongation at break, but this reflects a fine polycrystal which is a crystal grain. However, since the copper foil B is not developed due to the aggregate structure, the fatigue life is inferior. Further, when the copper foil C having an equal aggregate degree of 99.99% and the copper foil D having a purity of 99.999% is compared with the copper foil D having a purity of 99.999%, the bending fatigue property of the copper foil D is large, which is an excellent result. The two copper foils have the same oxygen concentration, and the amount of dispersion of copper oxide in the interior is also small. Since they are equivalent, they are not caused by the difference in copper oxide, but are caused by the difference in the elongation at break due to the difference in purity. As described above, as a result of the first embodiment, in order to obtain better characteristics than the general high-bending copper foil, it is necessary to have a basic crystal axis &lt;1 〇〇&gt; with respect to the thickness direction of the metal foil and the presence of the foil surface. 2 - 38 - 201146101 orthogonal axes in a certain direction within a certain direction, with a priority orientation field within ιο ° within each direction, occupying 50% or more in area ratio, and having a main orientation, and the ridge line in the curved portion The elongation at break of the metal foil in the normal direction of the cross section P of the wiring cut in the thickness direction of the metal foil is 3.5% or more. In addition, it is known that the purity is extremely high at 99.9 99% or more, and the orientation of the cube is developed to form a flexible circuit board in which the elongation at break is increased, and the principal stress and the main deformation are applied in the direction, and the fatigue life is long. [Example 2] Next, a single-sided copper-clad laminate using copper foil A and copper foil E produced in the same manner as in Example 1, as shown in Fig. 6, has a line width (1) of 150 μm. The wiring direction Η (Η direction) of the linear wiring 2 has an angle of 30° and 45° with respect to the MD direction ([1〇〇] axis), and a wiring pattern is formed in a space width (〇25 Ομηι). In the method of sampling for bending resistance test, which is described later, according to JIS 6471, it is possible to obtain a test having a width of 15 mm in the direction of the wiring direction of the circuit board, which is 150 mm in the longitudinal direction and perpendicular to the wiring direction Η. The flexible circuit board 5 is an example in which the angle between the wiring direction Η of the test flexible circuit board 5 and the MD direction is cut at an angle of 45°. The test flexibility obtained above is obtained. The circuit board 5 was subjected to the fatigue test of the reverse bending under the same conditions as in the first embodiment. The angle between the wiring direction Η of the test flexible circuit board 5 and the MD direction was the same, and the single sheet before the etching was used. Copper-clad laminate 4 dissolves the resin layer A tensile test of 150 mm x 10 mm sample cut by a method of -39-201146101 having an angle of 30° and 45° with respect to the direction of rolling in the longitudinal direction is used. That is, the fatigue test direction of the copper foil and the tensile test are performed. In the direction of stretching, the aggregate structure of one body is highly developed. Therefore, the main stress and the main deformation caused by the main deformation and tensile test in the same crystal orientation are shown in Table 2 °. , the main stress of the fatigue test and the tensile test of the copper foil A and the copper foil E. The fatigue test, -40- 201146101 [S] 遐 遐 毹 5 #5? 眯煺 眯煺 缄 £ 112£^«筮|| However, the stretch chain||钜坡111^3⁄4 Remarks Examples Embodiments Example Elongation at break (%) 〇r— ο to r- (D CD breaking strength (MPa) 00 r- r- 125 ! 115 118 Bending test life (times) 2200 2000 3800 3200 Wiring direction and rolling direction 1 angle (°) J Ο CO in inch ο CO ιο inch variety copper foil A copper foil A copper foil 铜 copper fan Ε ε: -41 - 201146101 From the test results shown in Table 2, by shifting the principal stress and the main deformation direction &lt;100&gt; In the orientation, the elongation at break is also significantly greater than the &lt; 1 〇〇&gt; orientation, especially in the case of 30. The fatigue life is longer with the elongation at break. As a result of Example 2, it is understood that there is a high correlation between the fatigue life of the relatively high-deformation curved circuit board which is repeatedly bent and the elongation at break of the copper foil constituting the wiring when the copper foil is highly aligned. As seen in Example 1, higher strength and ductility are obtained in the polycrystalline body, but it is not effective in high bending applications. Therefore, the relationship between the fatigue life as shown above and the elongation at break under conditions of a highly concentrated aggregate structure is an important role for the slip system, not limited to copper, even for the face centered cubic orientation with the same slip system. If the metal is also established, if the metal with different delamination energy is different, the estimated elongation at break is also larger, and the fatigue life can be expected to become larger. [K Example 3] A poly-proline solution a prepared by the same method as in Synthesis Example 1 was applied to a rolled copper foil having a purity of 99.9 mass% and a thickness of 12 μm, and dried (cured to a thickness of 2 μm). a thermoplastic polyimine), which is coated with polyamic acid b and dried (cured to form a low thermal expansion polyimine having a film thickness of 8 μm), and additionally coated with polyglycine a And drying (hardening to form a film thickness of 2 μίη of thermoplastic polyimide), as shown in the following conditions a to d, through the temperature of the highest temperature of 1 80~24 0 ° C in terms of integrated time as a load of 1 〇 Polyimine layer (resin layer) is formed under heating conditions. -42-201146101 Next, the length (TD direction) which is orthogonal to the rolling direction is 250 mm in the rolling direction (MD direction) along the copper foil. The single-sided copper-clad laminate 4 of Example 3 having a polyimine layer (resin layer) 1 having a thickness of μ2 μm and a copper foil 2 having a thickness of 12 μm was obtained by cutting out a rectangular shape having a width of 150 mm. The copper foil side of the single-sided copper-clad laminate 4 obtained above is covered with a predetermined mask, and is etched using a ferric chloride/copper chloride-based solution, and a line width of 150 μm and a space width of 2 5 0 μm are formed according to IPC specifications. The low-speed IPC test wiring 2 having linear wiring. In the manufacturing process, the maximum temperature of the heating condition at the time of forming the polyimide layer is 180 ° C (condition a), 20 (TC (condition b), 22 0 ° C (condition c), and 240 °) 4 levels such as C (condition d), and the wiring direction (Η direction) of the linear wiring 2 is 0 to 0, 2.9, 5.7, 9.5, 11.4 in the rolling direction (MD direction). °, 14〇, 18.40, 25°, 26.6〇, 30°, 40〇, 450, 55° &gt; 60° ' 63.4° , 78.6° , 80° ' 82.9° , 87.1 ° , 88 ° , and 90 ° A wiring pattern is formed in a manner of an angle of 22. Next, as shown in Fig. 8(b), an epoxy-based adhesive is used on the surface on the side of each wiring pattern to laminate the cover material 7 (CVK manufactured by Ozawa Seisakusho Co., Ltd.) -0515KA: thickness 12·5μιη). The thickness of the adhesive layer 6 composed of the adhesive is 15 μm in the portion where the copper foil circuit is not present, and 6 μm in the portion where the copper foil circuit is present. Η direction) is 15 cm in the longitudinal direction and 8 mm wide in the direction orthogonal to the wiring direction The test was carried out to obtain a flexible circuit board for testing which was sampled for IPC test. -43- 201146101 On the other hand, in order to investigate the characteristics of the copper foil monomer, a tensile test was carried out as shown below. The angle between the wiring direction Η of the flexible circuit board 5 and the angle of the MD direction is the same as the level of 22, and the resin layer is dissolved by the single-sided copper-clad laminate 4 before etching to form a copper foil. A rectangular sample having a length of 150 mm x a width of 10 mm cut in a direction in which the longitudinal direction is at a 22-degree angle with respect to the rolling direction is prepared. In this case, it is confirmed that in the process of dissolving the polyimine, in the copper foil The tensile test was carried out in the longitudinal direction at a distance of 1 〇〇 mm between the punctuation marks and a tensile speed of 10 mm / mi η. Further, the sample was subjected to analysis by the EBSP. In the case of the single-sided copper-clad laminate produced by the heat treatment conditions of the conditions a to d, five angles of 0°, 2.9°, 30°, 63.4°, and 78.6° with respect to the rolling direction were produced. Samples without wiring patterns In order to prepare the IPC test sample and the heat history, the simulated heat treatment was applied under the same conditions as the circuit formation etching, and the cover material was laminated under the same conditions. However, the influence on the copper foil structure was slight. The heat treatment conditions of the conditions a to d at the time of formation of the polyimine are determined by the copper foil structure, and then the heat treatment conditions of the four levels prepared by the EBSP measurement described above and the angles of five levels are obtained. The 20 pieces of copper foil of the condition are honed in the thickness direction of the substrate, and have a surface horizontal to the surface of the foil before the honing, and the foil surface of the copper foil is exposed. In addition, colloidal vermiculite was used for final honing, and EBSP was used to evaluate the structure of the copper foil crucible. The measurement area was 〇.8 mm x 1.6 mm, and the measurement interval was set to 4 μm. That is, the number of measurement points in the 1 field is 80000 points. -44 - 201146101 As a result, it was found that the sample obtained by heat treatment under the heat treatment conditions of the condition a to the condition d was formed with a cubic aggregate structure, and the main surface of the copper foil having a surface orientation and a rolling direction of {001} &lt;1〇〇&gt; Orientation. Then, based on the obtained results, the unit lattice axis &lt; 0 0 1 &gt; becomes 1 0 with respect to the thickness direction and the rolling direction of the copper foil. The number of points is counted'. The ratio to the total number of points is calculated, and the average 値 is obtained. The results are shown in Table 3 under the same heating conditions. The ratios between the samples in the same heating conditions are not more than 1%. The same heat treatment conditions are used to provide the total degree of accumulation shown in Table 3 throughout the copper foil. It can be seen that the higher the maximum heat treatment temperature and the higher the heat history, the more the recrystallization proceeds. The higher the degree of accumulation of the cube recrystallized aggregate structure. In addition, as a result of the orientation analysis in the foil surface, the main orientation of the sample cut out at the five angles of V ' 2.9°, 30°, 63.4°, and 7 8.6 ° with respect to the rolling direction has '[100], [20 10], [40 23 0], [120], [150] are roughly as intended. On the other hand, using the obtained EBSP data, the evaluation of the crystal grain size when the orientation difference of the adjacent crystal grains is 15° or more is analyzed as the crystal grain boundary when viewed from the normal direction of the foil surface, and the polycrystalline body is evaluated. The average particle size is obtained. The results are shown in Table 3. [Table 3] The thickness of the copper foil and the [001] accumulation degree of the rolling direction, and the crystal grain size of the heating condition foil. The rolling direction of the recrystallized grain in the thickness direction (Aim) Condition a 46% 49% 20 Condition b 50% 50% 25 Condition c 75% 85% 200 Condition d 98% 99% &gt;800 -45- 201146101 The IPC test system, as shown in the pattern diagram in Fig. 8, will be a curved form used in mobile phones and the like. A slip-bending test was performed after the simulation. In the IPC test system, as shown in Fig. 8, the bent portion was set at the determined gap length 8, and the one side was fixed by the fixing portion 9, and the sliding operation portion 1 on the opposite side was tested as a reciprocating motion as shown in the figure. Therefore, in the field of the stroke amount in the portion for the reciprocating motion, the substrate is subjected to repeated bending. In the present embodiment, the polyimine layer (resin layer) 1 is set to the outside, and the gap length is set to 1 mm, that is, the bending radius is set to 0.5 mm, and the stroke is set to 38 mm to perform the reverse slip. test. In the test, the resistance of the circuit of the flexible circuit board for the test was measured, and the degree of progress of the fatigue crack of the copper foil circuit was monitored by the increase in resistance. In the present embodiment, the number of strokes in which the resistance of the circuit reaches twice the initial enthalpy is taken as the circuit breaking life. In the test, the four heat treatment conditions of the above conditions a to d were carried out for a total of 88 levels of wiring patterns having an angle of 22 levels. In each of the test levels, four test pieces were measured, and the average number of strokes after the circuit was broken was obtained. When the copper foil after the rupture life of the circuit is observed by a scanning electron microscope and the copper foil is cut in the thickness direction perpendicular to the sliding direction, a difference in degree is observed, but on the resin layer side. The surface of the copper foil on the side of the cover material is cracked. In particular, a large number of cracks are introduced into the surface of the copper foil on the resin layer side corresponding to the outside of the curved portion. The average enthalpy of breaking the life of each level circuit and the elongation at break in the tensile test are shown in Table 4. In the angle field of Table 4, the length of the circuit -46 - 201146101 direction (wiring direction), that is, the cross section p of the wiring when the ridge line in the curved portion is cut in the thickness direction is only in the case of the low index direction. Display the face index. [Table 4] The fatigue life and the elongation at break in the IPC test are the angles formed by the MD direction (the surface index of the profile )). Bar 1 Cattle a Condition b Condition C, Cattle d Fracture life (times) Elongation at break (%) Fracture life (times) Elongation at break (%) Fracture life (times) Elongation at break (%) Fracture life (times) Elongation at break (%) 0° (100) 15200 3.5 16500 3.2 28600 2.9 32900 2.8 2〇14900 4.8 16500 3.4 28500 3.3 34100 3.2 2.9° [20 10) 15100 4.9 20200 3.6 30500 3.6 48200 3.5 5.7. (10 1 0) 14800 4.7 21000 3.9 33000 3.9 49100 4.0 9.5. (610) 15000 4.6 22500 4.5 33500 4.5 49900 4.6 11.4. (510) 14700 4.9 25800 4.8 38000 4.9 54200 5.0 14. (410) 15600 4.7 25600 5.6 39000 7.2 58400 7.5 18.4. (310) 14200 4.7 26200 5.7 38400 7.5 59800 8.2 25. 15200 4.6 27000 6.0 38900 7.6 58900 9.0 26.6° (210) 14100 4.8 27200 6.1 43000 7,8 62500 9.1 30. 14900 5.2 27500 6.2 45100 8.0 65900 11 40° 14000 4.5 27100 6.0 43100 7,9 63000 8.6 45. (110) 13800 4.7 26900 5.8 42900 6.8 62600 7.1 55° 12800 4.8 27000 6.0 43500 7.0 62200 8.1 60. 13800 5.0 27200 6.3 44900 8.7 65000 11.1 63.4° (120) 13400 4.9 24900 6,0 42500 8.0 62000 9.0 78.6° (150) 12500 4.7 24800 5.8 39000 4.5 58200 4.8 80. 12800 4.6 20200 5.9 32500 4.2 48900 4.2 82.9. (180) 12700 4.5 19900 4.6 32400 3.8 46800 3.7 87.1. (1 20 0) 13000 4.5 18900 4.7 32200 3.8 45000 3.5 88° 13000 4.0 15800 3.4 28000 3.3 31000 3.0 90. (010) 12900 3.0 15900 3.3 27900 2.7 30900 2.5 It is known that the fracture life (fatigue life) in the IPC test is greatly dependent on the angle between the length direction of the circuit (H direction) and the direction of the rolling direction (MD direction) -47-201146101 degrees, also That is, the normal direction of the wiring cross section when the ridge line in the curved portion is cut in the thickness direction is at an angle to [1 〇〇]. This orientation dependence appears under the condition b, the condition c, and the condition d. The higher the cumulative degree of the cube orientation, the greater the fatigue life for the repeated bending, and the greater the orientation dependence. Regarding the orientation dependence, it was confirmed that the thickness direction of the metal foil was such that the area of the copper [ 〇〇 1 ] within 10° of the azimuth difference was occupied by the EBSP method and the area ratio was 50% or more. ;001>The main orientation is preferentially aligned toward the thickness direction of the metal foil, and the area ratio is more than 50% by the EBSP method in the field of the [1〇〇] axis of copper within 10° of the azimuth difference. The way, [100] the main orientation appears in the metal foil surface as a priority alignment. In particular, when the thickness direction and the rolling direction indicate the condition c having an area ratio of 75% or more and 85% or more and a cube orientation is high, the fatigue life is large and the effect of the orientation dependency is large. When the thickness direction and the rolling direction indicate an area ratio of 9 8% or more and 99% or more, and the cube azimuth is extremely high, the fatigue life is larger and the orientation dependence effect is greater. When the results of the condition b, the condition c, and the condition d are reviewed in detail, the normal direction of the wiring cross section P when the ridge line in the curved portion is cut in the thickness direction, that is, the principal stress direction is from the copper foil &lt;100&gt; The main azimuth shifter has a higher fatigue life in a relatively curved circuit. In the IPC test of the present embodiment, it is seen that the main deformation direction of the opposite bending portion, that is, the normal direction of the cross section of the wiring when the ridge line in the curved portion is cut toward the thickness direction, has 2.9° to 8 7 . When the angle of the situation is. When the ridge line in the curved portion is cut in the thickness direction by the surface index, the cross section P of the wiring when the thickness is -48-20 201146101 (the opening time of the opening is 0). [〇〇1] is the range in which the ribbon axis '(20 1 〇) passes (lio) to (1 〇). The larger the effect is the main deformation side of the opposite bending portion, that is, the relative bending portion When the ridge line is cut in the thickness direction, the normal direction of the wiring section has an angle of 1 i · 4 to 7 8.6. The surface is indexed by the ridge line in the curved portion and cut in the thickness direction. The cross section P is such that [〇〇1] is a crystal ribbon axis, and (5 i 〇) passes through 1 1 〇) to (1 50). The bending property is also 2 6.6 in the normal direction of the main bending direction of the curved portion, i.e., the normal direction of the cross section of the wiring when the ridge line in the curved portion is cut in the thickness direction. ~6 3 · 4. The angle will become higher. The most excellent are 30° and 60. When the situation. If it is represented by a face finger, the profile P is [0 0 1] as the band axis, and the range from (2 1 0 ) to (11〇) to (120) is the most excellent (40 23). ) and when (2 3 4 0 0 ) is nearby. When these results are compared with the elongation at break, it is understood that the basic crystal axis of the unit cell made by face center cube &lt;1 〇〇&gt; is relative to the thickness of the metal foil and in a certain direction existing in the foil surface. In the two orthogonal axes, the priority alignment field within 10° of each other has an area ratio of 50% or more. When the main orientation is present, the cross section of the wiring which is cut toward the thickness direction of the metal foil with respect to the ridge line in the curved portion The metal foil in the normal direction has an elongation at break of 3.5% or more, and the main stress and the main deformation are bent in relation to the orientation thereof, and have good bending fatigue characteristics. On the other hand, when the area ratio of the first alignment field is 49% or less, even if the crack elongation of the direction is 3.5% or more, good bending fatigue cannot be obtained. -49-201146101 [Example 4] A copper foil C having a purity of 99.99% was applied by heat treatment (preheat treatment) at a temperature of 5 °C to 400 °C for 30 minutes in an Ar gas flow, and was applied in the same manner as in Example 1. The proline solution a is coated and dried (hardened to form a thermoplastic polyimide having a film thickness of 2 μm), and the polyamid acid b is coated thereon and dried (cured to form a film thickness of 9 μm). a low-heat-expandable polyimine), which is additionally coated with poly-proline acid a, and dried (hardened to form a thermoplastic polyimide having a film thickness of 2 μm), and is integrated at a temperature of 300 to 360 ° C. The time is calculated as a heating condition of 5 minutes or more, and a polyimine layer composed of a three-layer structure is formed. Then, the rolling direction (MD direction) of the copper foil is cut to a length of 250 mm, and the direction orthogonal to the rolling direction (TD direction) is a rectangular shape having a width of 50 mm, as shown in FIG. A single-sided copper-clad laminate 4 having a polyimide layer (resin layer) 1 having a thickness of 13 μm and a copper foil 2 having a thickness of 9 μm was obtained. The tensile modulus of the entire resin layer at this time was 7.5 GPa. In the single-sided copper-clad laminate 4 obtained as described above, colloidal vermiculite was used for the rolling surface 2a of the copper foil 2, and after mechanical and chemical honing, the orientation was analyzed by an EBSP apparatus. The apparatus used was an FE-SEM (S-4 100) manufactured by Hitachi, Ltd., an EBSP device manufactured by TSL Corporation, and a software (OIM Analysis 5.2). The measurement field is a field of about 800 μm χ 1 6 0 0 μιη, and the acceleration voltage is 20 kV and the measurement phase interval is 4 μm. The evaluation of the orientation is expressed in the thickness direction of the tank and the rolling direction of the tank, and the ratio of the measurement point within &lt;100&gt; within 10° to the entire measurement point. Measurement -50- 201146101 The number system is implemented for five samples of different varieties, and the decimal point of the percentage is rounded off to the second place. Further, using the obtained data, the orientation of the adjacent crystal grains was 15 . The above is used as the crystal grain boundary to evaluate the crystal grain size. With regard to the multi-junction, the average particle size is not found in the body. The results are shown in Table 5. -51 - 201146101 [s^] Remarks Comparative Example Comparative Example Example Example Comparative Example Elongation at break in the rolling direction (%) &lt;N CO CVJ CO ιο CO CO CO ι- 断裂 Fracture strength in the rolling direction (MPa) L〇r- r~ l〇v T— iO r~ t— 卜r- τ— 10 r&quot; τ— ιο ο ι— bending test life (times) omo T- oo production t— oo inch ο ο (0 τ — Ο ο 00 τ— ο ο τ — S m &gt;800 &gt;800 &gt;800 &gt;800 &gt;800 &gt;800 ρ,Μ •ES mvt, 0) (D 0) IT) 卜σ&gt; 00 σ (Ν 0) σ&gt; ω 0) σ&gt; ο 6 ο 1^ 鹄its SV 漶SS T- 10 0) σ) CO σ&gt; ο 00 0) ο 0) σ&gt; ιη σ&gt; 0) 0) σ&gt;σ&gt; Pre-heat treatment temperature ro ο 00 ο 〇 04 2 5 0 ο ο C0 〇〇-52- 201146101 It can be seen that the copper foil C is formed with a cube assembly structure, and the copper foil surface orientation and rolling direction have {001} &lt;1〇〇&gt;The main orientation. This is because the copper foil which has been subjected to the calendering process is recrystallized by the heat of the preliminary heat treatment and the hardening of the polyimide, and the recrystallized aggregate structure is formed. Here, the greater the degree of alignment of the preliminary heat treatment temperature '{001} &lt;1〇〇&gt;. Further, the orientation other than the orientation of &lt;100 &gt; is confirmed by the EBSP apparatus as described above, and has an orientation of &lt;212&gt; with respect to the rolling direction, and the recrystallized residual orientation of the circle having a diameter of 5 μm or less is dispersed into an island shape. However, at 4 0 0. (In the case of the copper foil subjected to the preliminary heat treatment, the island-like structure as described above is hardly found. Among them, the area ratio of the confirmed island-like structure is small and is 2% or less, so that the crystal grain having a cubic orientation is recrystallized. The size of the recrystallized grains is 9 μηι in the thickness direction and 800 μπι in the thickness of the box. Then, the predetermined mask is covered on the single side obtained above. The copper foil 2 side of the copper clad laminate 4 is etched using a ferric chloride/copper chloride-based solution, as shown in Fig. 6 (but the wiring direction Η is at an angle of 0 ° with the MD direction), and the line width is (1) The wiring direction Η (Η direction) of the linear wiring 2 of 150 μm is parallel to the MD direction (&lt;1〇〇&gt; axis), and wiring is formed so that the space width (s) is 250 μm. Then, as shown in the sampling for the bending resistance test which will be described later, the wiring direction Η along the circuit board is obtained in accordance with JIS 6471, and has a length of 15 mm in the longitudinal direction and a direction orthogonal to the wiring direction Η. Flexible test with a width of 1 5mm Circuit board 5. Using the test flexible circuit board obtained above, the MIT bending test was performed in accordance with JIS C501 6. The pattern of the test is shown in Fig. 7. -53- 201146101 The apparatus was manufactured by Toyo Seiki Co., Ltd. (STROGRAPH- Rl), one end in the longitudinal direction of the test flexible circuit board 5 was fixed to the holding jig of the bending test apparatus, and the other end was fixed by a weight, and the vibration speed was 150 times at the center of the nip portion. The condition of the minute is alternately rotated by 135±5 degrees, and the radius of curvature is 0.8 mm, and the number of times until the conduction of the wiring 2 of the circuit board 5 is blocked is obtained as the number of bending times. The ridge line formed in the curved portion is curved so as to be orthogonal to the wiring direction 配线 of the wiring 2 of the test flexible circuit board 5, so that the principal stress and the main deformation applied to the copper circuit are parallel to the rolling direction. Tensile stress and tensile deformation. When the circuit was observed from the thickness direction of the copper foil after the bending test, it was confirmed that the vicinity of the ridge line of the curved portion was approximately the same as the rolling direction. A crack occurred in a vertical direction and a broken line occurred. The results of the bending life are shown in Table 5. The bending life of Table 5 is an average of the results of preparing five test flexible circuit boards for each copper foil preliminary heat treatment temperature. As can be seen from the results shown in Table 5, the bending fatigue life is particularly large when the cumulative degree of the cubic aggregate structure is 98.0% or more and 99.8%. Next, in order to investigate the dominant factor of the bending life, the principal stress of the bending, the main deformation direction, In other words, the tensile test is performed in parallel in the rolling direction. In order to investigate the characteristics of the copper foil monomer obtained by the preliminary heat treatment temperature, the resin layer is dissolved by the single-sided copper-clad laminate 4 before etching, and the copper foil is used. Body tensile test. It was confirmed that there was no change in the structure of the copper foil during the dissolution of the polyimide. The tensile test was performed by cutting the copper foil toward the rolling direction (MD direction) -54-201146101 into a length of 50 mm, and cutting into a sample having a width of 10 mm in the vertical direction of the foil surface, with a distance between the punctuation points of 10 mm, toward The measurement was carried out in the longitudinal direction at a tensile speed of 10 mm/min. In the measurement, seven samples were prepared for each of the preliminary heat treatment temperatures of each of the copper foils, and the fracture stress (breaking strength) obtained by the measurement and the average enthalpy of the elongation at break were shown in Table 5. Contrary to the results so far, the elongation at break is larger in the field where the degree of accumulation (%) is 9 8.0 % or more and 9 9 · 8 % or less in the range of the rupture elongation. . On the other hand, in the copper foil in which the island-like structure has disappeared, the elongation at break becomes small. This system is presumed to be related to the slip surface. It has been confirmed from the above that the elongation at break is strongly correlated with the bending fatigue life. In other words, it is understood that the aggregated degree (%) of 9 8.0% or more and 9.9.8% or less is highly developed, and the elongation at break is 3.5% or more, and the bending fatigue life is increased. On the other hand, a copper foil was produced under the same conditions using a fine copper containing 0.03 mass% of oxygen and a purity of 99.9% under the same conditions, and the test was carried out under the same conditions. The result was that even if the &lt;1 〇〇&gt; accumulation degree (%) was 98.0 Similarly, in the same manner, the elongation at break decreases as the degree of accumulation increases, and 3.5% or more of the copper foil is not obtained, and the fatigue life of 1,000 or more times is not obtained. [Industrial Applicability] The flexible circuit board of the present invention can be widely used in various electronic and electrical equipment, and the circuit board itself is bent, twisted, or deformed according to the operation of the loaded machine, either Both are adapted to have a curved portion for use. In particular, the flexible circuit board of the present invention has a curved portion structure with a bending durability of -55 to 201146101, and is therefore suitable for being frequently folded and loaded with repeated operations such as sliding bending, hinge bending, and sliding bending. When the machine is miniaturized, it is formed when the curved portion is formed. Therefore, various types of electronic equipment, such as thin-type displays, hard disks, printers, and DVD devices, which are required to be durable, are used. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a relationship between a plane obtained by rotating a crystal ribbon axis in a crystal structure of a cubic lattice system. Fig. 2 is a perspective view of a (3 00) standard projection view. Fig. 3 is a perspective view showing bending of a flexible circuit board. Fig. 4 is a plan explanatory view showing the relationship between the wiring crystal axes in the flexible circuit board, (a) and (b) are flexible circuit boards, and (c) and (d) are conventional circuit boards. Fig. 5 is a squint explanatory view of a single-sided copper clad laminate. Fig. 6 is a plan view showing a state in which a flexible circuit board for a test is obtained by a single embodiment in the embodiment of the present invention. Fig. 7 is an explanatory view of the MIT bending test apparatus. Fig. 8 (a) is an illustration of a flexible electrical cross-section of the test used in the IPC bending test. The curved or curved curved or curved radius is extremely small. The mobile phone and thin can be used for the ribbon shaft and the shape. The section of the state is said to be a junction with a metal foil. The flexible copper-clad laminate of the technique of the present invention is shown. Fig. 8 (X-X'-56 - 201146101 of the b-channel substrate [Explanation of main component symbols] 1 = Resin layer 2: Wiring (metal) 2a: Rolling surface 2 b: Side 3: Connector terminal 4: Single-sided copper clad laminate 5: Test flexible circuit board 6: Adhesive layer 7: Cover material 8: Gap length 9: Fixing portion 10: Slip operation portion 2 1 : Normal direction L of cross section P: Ridge line P: section of the wiring when cut from the ridge line in the curved portion toward the thickness direction - 57-

Claims (1)

201146101 VII. Patent application scope: 1. A flexible circuit board having a resin layer and a wiring formed of a metal foil, and having a flexible circuit board having a bent portion at at least one portion of the wiring, The feature is that the metal foil is composed of a metal having a face-centered cubic structure, and the basic crystal axis of the unitary lattice of the face-centered cubic structure &lt;100&gt; is opposite to the thickness direction of the metal foil and exists in the foil surface. The two orthogonal axes in a certain direction, the priority alignment field within 10° of the azimuth difference is 50% or more in area ratio, and the cross section of the wiring which is cut toward the thickness direction of the metal foil by the ridge line in the curved portion The elongation at break of the metal foil in the normal direction is 3.5% or more and 20% or less. 2. The flexible circuit board according to claim 1, wherein the metal foil is made of a copper foil having a purity of 99.999 mass% or more. 3. The flexible circuit board according to claim 1 or 2, wherein the metal foil is a copper foil, and the crystal grain size when viewed from the normal direction of the foil surface is 25 μm or more. 4. The flexible circuit board according to any one of claims 1 to 3, wherein the metal foil has a thickness of 5 μm or more and 18 μm or less. The flexible circuit board according to any one of claims 1 to 4, wherein the cross-section of the wiring is from the (100) pair (110) with [〇〇1] as a ribbon axis. Any plane included in the range of (20 1 0) to (1 20 0 ) in the direction of rotation forms the principal orientation. 6. The flexible circuit substrate of the fifth aspect of the patent application is in which the section of the wiring is in the solid triangle of the (1 〇〇) standard projection drawing 'bit-58- 201146101 to indicate (2 〇1 〇 Any point on the point where the point is connected to the point representing (11 0 ). The circuit substrate according to any one of claims 1 to 6, wherein the wiring is orthogonal to the ridge line in the opposite curved portion. The circuit substrate according to any one of claims 1 to 7, wherein the resin layer is composed of polyimide. 9. The compliant substrate of any one of clauses 1 to 8, wherein the forming of the substrate is accompanied by any repetitive action selected from the group consisting of sliding bending, folding, hinge bending, and slip bending. The way to use it. 10. An electronic device characterized by being mounted with a flexible circuit substrate according to any one of items 1 to 9. 11. A bent portion structure of a flexible circuit board, comprising a grease layer and a wiring formed of a metal foil, wherein a curved portion of the flexible circuit board having at least one bent portion of the wiring is characterized by : The metal foil is composed of a metal having a face-centered cubic structure, the basic crystal axis of the unit cell of the heart-cubic structure &lt; 丨 00 &gt; the relative thickness direction, and 2 in a certain direction existing in the foil surface The preferential alignment field within 10° of the difference in orientation difference is the area ratio above and the elongation of the metal foil relative to the thickness of the metal foil from the ridge line in the curved portion _ 03⁄4 ΙΒ, the normal direction of the line @profile Ρ Above, 20% or less. The line segment is flexible. The directional shape is flexible and flexible. The bending part is patented. There is a part of the tree, and the surface of the metal foil is perpendicular to the axis. The 50% direction is cut to 3. 5 % -59-