TWI532858B - Copper foil, copper clad laminate, flexible circuit substrate, and copper clad laminate manufacturing method - Google Patents

Description

Copper foil, copper-clad laminate, flexible circuit board, and copper-clad laminate manufacturing method

The present invention relates to a copper foil having high flex fatigue durability and a copper clad laminate using the copper foil, and a flexible circuit board. And a method of manufacturing a copper-clad laminate, in particular, a copper foil capable of producing a flexible circuit board having durability and flexibility, and using a copper-clad layer of the copper foil A method of manufacturing a plywood, a flexible circuit board, and a copper clad laminate.

A flexible printed circuit board formed by a wiring made of a resin layer and a metal foil can be bent, including a movable portion in a hard disk and a mobile phone. a hinge portion or a slide sliding part, a head portion for a printer, a light pick-up portion, a note book type personal The mobile part of the computer is widely used in various electronic devices. On electrical equipment. Further, recently, with the miniaturization, thinning, and high functionality of such devices, it is necessary to be able to fold a flexible circuit substrate in a limited space for storage, or electrons. Flexibility of various actions of electrical equipment. Therefore, mechanical characteristics such as further strength of the flexible circuit board are required in order to cope with the method in which the radius of curvature in the flexure portion is smaller or the method of frequently repeating the bending. mention Rise.

In general, it is not a resin layer but a wiring because of the repetition of the bending or the strength difference of the bending radius, and the like. If the film cannot be tolerated, cracks or cracks may occur in a part of the wiring. Can no longer be used as a circuit board. Then, for example, in order to reduce the bending stress on the wiring of the hinge portion, a flexible circuit board that is routed so that the rotary axis can be inclined is proposed (refer to Patent Document 1). Alternatively, a method of spiraling one or more spiral portions in the direction of rotation of the hinge portion and increasing the number of windings to reduce the change in the diameter of the spiral portion due to the opening and closing operation to reduce the damage (see Patent Document 2). However, these methods limit the design of the flexible circuit substrate.

On the other hand, the intensity of the (200) plane obtained by X-ray diffraction (X-ray diffraction in the thickness direction of the copper foil) of the rolled surface of the rolled copper foil (I) In the case where the intensity (I ₀ ) of the (200) plane obtained by the X-ray diffraction of the fine powder copper is I/I ₀ >20, the flexibility is excellent (refer to Patent Documents 3 and 4). ). That is, since the copper direction of the recrystallization aggregation texture belonging to copper is more developed, the flexibility of copper is improved, and a cube aggregation texture is known. The growth degree is defined as the above-mentioned parameter (I/I ₀ ), and is suitable as a copper foil for the wiring material of the flexible circuit board. In addition, there is a report that a concentration of solid solution in the range of copper contains Fe (iron), Ni (nickel), Al (aluminum), Ag (silver) and other elements, and according to the established conditions. The rolled copper alloy foil obtained by annealing to recrystallize the shearing deformation along the slip plane, and the fact that the flexibility is excellent (refer to the patent literature) 5).

In addition, a copper foil containing impurities such as oxygen or silver, and a copper foil having a purity of about 99% to 99.9% by mass, may be used for the flexible circuit board which requires high flexural properties. In the present description, unless otherwise noted, the purity is expressed in terms of mass concentration. In addition, as for the test grade, there are examples of tough-pitch copper or oxide-free oxygen-free copper which is used in a wide range of conductors for cables (refer to Patent Documents 3 and 4). . Impurities of tough copper, in addition to hundreds of ppm of oxygen (mostly contained in copper oxide), still contain silver, iron, sulfur, phosphorus and the like. Oxygen-free copper is usually copper with a purity of about 99.96 to 99.995%, and is copper which has been greatly reduced in oxygen to less than 10 ppm. It is reported in the above-mentioned Patent Documents 3 and 4 that the flexural fatigue characteristics of the copper foil produced by the oxygen-free copper are superior to that of the tough copper foil, and are caused by the presence or absence of copper oxide. Furthermore, if it is desired to further increase the purity of such copper, it is necessary to remove impurities such as silver, phosphorus, sulfur, and the like.

[Previous Technical Literature] [Patent Document]

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2002-171033

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2002-300247

[Patent Document 3] Japanese Patent Laid-Open Publication No. 2001-58203

[Patent Document 4] Japanese Patent No. 3009383

[Patent Document 5] Japanese Patent Laid-Open Publication No. 2007-107036

Under the circumstance, the inventors of the present invention have found that the flexible circuit board is not limited in design, and the results of intensive research on the flexible circuit board having durability such as repetition of bending or small curvature radius are also provided. It has been found that the present invention has finally been completed by using a copper alloy foil which is highly oriented even with the addition of an alloy component, to obtain a flexible circuit substrate excellent in flexural durability or flexibility.

Therefore, an object of the present invention is to provide an excellent durability. For example, in a flexible circuit board, when a wiring is formed, a hinge portion or a guide sliding portion of a mobile phone or a small electronic device or the like may have a radius of curvature. A copper alloy foil (hereinafter, abbreviated as "copper foil") which is excellent in durability and excellent in flexural durability can be exhibited under severe use conditions.

Moreover, an object of the present invention is to provide a copper-clad laminate which can obtain a flexible circuit board excellent in durability and the like using the above-mentioned copper foil, and a flexible circuit board therefor.

Furthermore, another object of the present invention is to provide a method for producing a copper-clad laminate suitable for producing a flexible circuit board having excellent durability and the like.

In order to solve the above problems of the prior art, the gist of the present invention has the following constitution.

(1) A copper foil comprising Cu (copper) copper foil having Mn (manganese) of 0.001% by mass or more and 0.4% by mass or less and having an unavoidable impurity and a remainder, characterized by a unit cell of copper (unit) The basic crystal axis <100> of the lattice is the orthogonal axis of the thickness direction of the copper foil and the direction existing in the foil surface, and the azimuthal difference is 15°. The preferred orientation region within the area is 60% or more in terms of area ratio.

(2) The copper foil according to the above (1), which contains 0.001% by mass or more and 0.1% by mass or less of Mn, and contains 0.005% by mass or more and 0.2% by mass or less of Ti (titanium) or 0.005% by mass or more and 2% by mass. At least one of the following Al (aluminum).

(3) The copper foil according to (1) or (2), which contains 0.06 mass% or less of Mn.

(4) A copper foil containing a substance selected from the group consisting of Ca (calcium), La (yttrium), Ce (yttrium), Pr (yttrium), Nd (yttrium), Sm (yttrium), Eu (yttrium), and Gd (yttrium). At least one element of the group of Dy (镝), Ho (鈥), Er (铒), Tm (銩), Yb (镱), and Y (钇) is 0.005 mass% or more and 0.4 mass% or less, and the remainder The copper foil having a copper content of 99.6 mass% or more and 99.999 mass% or less is characterized in that the basic crystal axis of the unit crystal lattice of copper is <100>, which is formed in the thickness direction of the copper foil and in a direction existing in the foil surface. The two orthogonal axes, the preferred orientation regions within 15° of each azimuth difference, account for more than 60% of the area ratio.

(5) The copper foil according to (4), which contains 0.005 mass% At least one of 0.2% by mass or less of Ti or 0.005 mass% or more and 0.395 mass% or less of Al.

(6) The copper foil according to any one of (1) to (5) wherein the content of oxygen is less than 0.1% by mass.

(7) A copper-clad laminate having a copper foil layer formed of the copper foil according to any one of (1) to (6) and a resin layer laminated thereon.

(8) The copper-clad laminate according to (7), wherein the thickness of the copper foil layer is 5 μm or more and 18 μm or less, and the thickness of the resin layer is 5 μm or more and 75 μm or less.

(9) The copper-clad laminate according to (7) or (8), wherein the resin layer is made of polyimine.

(10) A flexible circuit board, characterized in that the copper foil layer of the copper-clad laminate according to any one of (7) to (9) is etched to form a predetermined wiring, and the wiring is Use at least one part to form the flexure.

(11) The flexible circuit board according to (10), wherein any one of the repetitive movements in which the companion is selected from the group consisting of sliding flexing, bending flexing, hinge flexing, and bending of the guide plate is formed. The user of the way of flexing the part.

(12) An electronic device comprising the flexible circuit board according to (10) or (11).

(13) A method for producing a copper-clad laminate, comprising a method of producing a copper-clad laminate having a copper foil layer and a resin layer, wherein the composition contains Mn in an amount of 0.001% by mass or more and 0.1% by mass or less. Have no Avoiding the impurities and the surface of the cold rolled copper foil of Cu, coating the polyaminic acid solution and performing heat treatment, or superimposing the polyimide film to perform thermo compression bonding. By forming a resin layer made of polyimine on a cold rolled copper foil and recrystallizing the cold-rolled copper foil to form a basic crystal axis of the unit crystal of copper <100>, The preferred orientation area of the thickness direction of the copper foil and the two orthogonal axes formed in a certain direction of the foil surface, within 15 degrees of each azimuth difference, occupying 60% or more of the copper foil by area ratio Floor.

(14) The method for producing a copper-clad laminate according to the above aspect, wherein the cold-rolled copper foil further contains 0.005 mass% or more and 0.2 mass% or less of Ti, or 0.005 mass% or more and 2 mass% or less of Al. One.

(15) The method for producing a copper-clad laminate according to the above aspect, wherein the cold-rolled copper foil contains 0.06 mass% or less of Mn.

(16) A method for producing a copper-clad laminate, which is a method for producing a copper-clad laminate having a copper foil layer and a resin layer, comprising: a pair selected from the group consisting of Ca, La, Ce, Pr, Nd, Sm, and Eu , at least one element of the group of Gd, Dy, Ho, Er, Tm, Yb, and Y is 0.005 mass% or more and 0.4 mass% or less, and the remaining copper is 99.9% by mass or more and 99.999 mass% or less of the cold rolled copper foil surface. , coating the polyaminic acid solution and performing heat treatment, or superimposing the polyimide film to perform hot press bonding, thereby forming a resin layer made of polyimine on the cold rolled copper foil while making cold rolled copper The foil is recrystallized, and the basic crystal axis of the unit crystal lattice of copper is <100>, and the thickness direction of the copper foil and the two orthogonal axes formed in a certain direction in the foil surface can be formed. The preferred orientation area within 15° of each azimuth difference accounts for more than 60% of the copper foil layer in terms of area ratio.

(17) The method for producing a copper-clad laminate according to the above aspect, wherein the cold-rolled copper foil contains 0.005 mass% or more and 0.2 mass% or less of Ti or 0.005 mass% or more and 0.395 mass% or less of Al.

(18) The method for producing a copper-clad laminate according to any one of (13) to (17) wherein the coated polyaminic acid solution is subjected to heat treatment to form a resin layer at a temperature of 280 ° C. Above 400 ° C.

The method for producing a copper-clad laminate according to any one of the aspects of the present invention, wherein the polyimide film is subjected to thermocompression bonding to form a resin layer at a temperature of from 280 ° C to 400 ° C. .

According to the present invention, even if the flexure portion forms a wiring when the flexible circuit substrate is flexed, it is difficult to cause metal fatigue, and has excellent durability against stress and strain. Sex. Therefore, the design of the flexible circuit board is not limited, and the bending of the bend or the curvature of the radius of curvature is also tolerable, and the flexible circuit board having excellent flexibility is obtained. A thin mobile phone, a thin display, a hard disk, a printer, a DVD (multi-function digital video disc) device, etc., can realize an electronic device with high durability.

[Best Embodiment of the Invention]

Hereinafter, the present invention will be described in detail.

The copper foil of the present invention is a pair of repeated load (load) or deformation, and it is difficult to cause fatigue cracking. For the purpose of realizing such a copper foil, the results of the two kinds of alloy compositions are successfully produced, and it is difficult to produce metal fatigue. Forced and deformed copper-clad laminate or flexible circuit board with excellent durability. The copper foil having the first alloy composition contains Mn in an amount of 0.001% by mass or more and 0.4% by mass or less as a composition, and has an unavoidable impurity and a residual portion of Cu, and is characterized by a basic crystal of a unit lattice having copper. The axis <100> is a pair of orthogonal axes formed by the thickness direction of the copper foil and a direction existing in the foil surface, and the preferred orientation area within 15 degrees of each azimuth difference, in terms of area ratio, in the occupancy 60 More than % of the organizations (hereinafter referred to as "the copper foil of the first invention"). Further, the copper foil having the second alloy composition contains at least one selected from the group consisting of Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y. The element is 0.005 mass% or more and 0.4 mass% or less, and the remaining copper is 99.6% by mass or more and 99.999 mass% or less, and is characterized in that the unit lattice having copper is <100>, and the thickness direction of the copper foil is present in the foil. Two orthogonal axes formed in one direction in the plane, and a preferred orientation region within 15° of each azimuth difference, in an area ratio of 60% or more of the tissue (hereinafter referred to as "the copper foil of the second invention" ").

First, the specifications regarding the material structure of the copper foils according to the first and second inventions will be described.

In general, material organization can have a large impact on the fatigue properties of materials. If the organization is fine, although the strength or breaking ductility will be improved, on the other hand, the grain boundary (grain) Boundary will become the cumulative plane of the reaping. Further, the microscopic stress concentration at the time of deformation due to the anisotropy of each crystal grain of the azimuth of the crystal grains deteriorates the fatigue characteristics. The present invention provides a copper foil having excellent fatigue characteristics, a copper foil having excellent deformation characteristics of a flexural portion having a curvature radius of 2 mm or less after forming a wiring of a flexible circuit board, and a copper foil having excellent fatigue characteristics. It is better to have no grain boundary in the middle, and it is highly oriented, and the three basic crystal axes of copper are all suitable. Since the three basic crystal axes <100> are orthogonal to each other, if two of the axes can be determined, all the axes can be determined. That is, the basic crystal axis of the unit cell of copper <100>, there is a need to have two orthogonal axes of the thickness direction of the copper foil and a direction existing in the foil surface, and each orientation difference is within 15°. The preferred orientation area accounts for 60% or more, preferably 80% or more, in terms of area ratio. In particular, in the case of forming a flexing portion such as a flexing portion having a curvature radius of 0.8 mm or less, it is preferable to use 95% or more of the composition, and more preferably 98% or more.

Since the grain orientation in the center of the preferred orientation region is simply referred to as the main aziluth of the aggregation organization, the first and second copper foils of the present invention can be said to have the thickness direction of the copper foil. At the same time as the main orientation of <100>, the foil surface of the copper foil has a main orientation of <100>. That is, the copper foil of the present invention needs to have a <100> orientation in the thickness direction of the foil, and a short orientation in which the <100> orientation orthogonal to the orientation is used as the main orientation. Aggregation of cubic azimuth (aggregation) Organization). It is preferable that the integration level of the cube orientation is higher, and the copper foil of the present invention preferably has a crystal grain size of more than 800 μm in the foil surface due to the development of such agglomerated structure. It is preferable to have a structure in which the crystal grain size penetrates the thickness direction of the foil. In the following description, unless otherwise noted, the description is common to the copper foils according to the first and second inventions.

The copper foils according to the first and second inventions may each be either rolled copper or electrolytic copper, but are preferably rolled copper for obtaining high directing property. . In the case of copper, it has been known to select a roll condition and a heat treatment condition, and specifically, it is preferable to carry out roll processing in accordance with a large cold working ratio (final rolling ratio of 90% or more). And work hardening to accumulate deformation and then apply heat to recrystallize it. One of the recrystallized structures of the copper processed by the roll is a cubic aggregate structure having a thickness of <100> in the thickness direction of the foil and a <100> orientation in the direction of the roll.

The priority indicating the preferred orientation of the aggregated organization, that is, the index indicating the directing degree or the integral degree, but may be obtained by electron diffraction. The statistic data of the statistics of the three-dimensional azimuthal data. Therefore, in order to define the aggregated structure according to the three-dimensional degree of integration, it is possible to specify the area ratio of the preferred orientation area in which the main orientation of the aggregated structure enters within 15°.

That is, as to the crystal azimuth of the predetermined surface of the copper foil, for example, an EBSD (electron back scattering diffraction) method or an ECP (electron channeling pattern) can be used. It is confirmed by an electron diffraction method such as a method or an X-ray diffraction method such as a micro Laue's method. The EBSD method is a diffraction image called pseudo KIKUCHI ray which is emitted from each crystal plane when a converging electron beam is irradiated onto the surface of the sample to be measured. (diffraction figure) Analyzes the crystal, and measures the crystal azimuth distribution of the measured object from the orientation data and the location information of the measurement point, and the X-ray diffraction method is capable of analyzing the aggregation of the microscopic region. The crystal orientation of the tissue. For example, crystal azimuth can be specified in each micro-region, and these are linked for mapping, and the same color is used to coat the plane azimuth between the mapping points. If the inclination angle (azimuth difference) is below a certain value, and the distribution of the area (grain) having the same plane orientation is particularly remarkable, the azimuth mapping image can be drawn. Further, the orientation may be defined by including an azimuth plane having a certain angle within a predetermined angle, and the ratio of the plane orientations may be extracted by the area ratio. In the EBSD method, since the area ratio of the region within a certain angle is calculated from a specific orientation, when considering the formation of the wiring of the flexible circuit board, in the present invention, it is preferable to be in the wiring. The region of the flexion is a large region, and the electron beam is finely scanned in such a manner as to be sufficient to calculate the area ratio to obtain the average information. In the present invention, it is considered that a region of about 0.005 mm ² is selected under the size of a wiring circuit formed on a flexible circuit board, and it is sufficient to measure 1000 points or more in order to calculate an average area ratio.

<The copper foil of the first invention>

Next, the copper foil of the first invention will be described with respect to the specifications of the alloy composition.

In general, alloying elements are those that increase the strength of metals by solid dissolving tempering. However, on the other hand, almost all of the alloying elements of copper with a face-centered cubic structure reduce the laminated deficiency energy to facilitate spreading. Bit. Therefore, it is difficult to cause a cross-slip when indexing is performed at the time of deformation, so that accumulation of localized indexing is liable to occur. As a result, it also has the effect of reducing the fatigue characteristic at the time of repeated deformation. It has been found that Mn may be less effective than other alloys in reducing the lamination defect energy of copper. In the case of having the same structure, when copper having a predetermined amount of Mn is compared with copper which is not contained, copper having Mn has an increase in breakage when a tensile stress is applied to one direction in the foil surface. The large effect, that is, even if the alloy component is added, it is highly oriented, and its breaking property realizes a copper alloy foil having a large face-centered cubic crystal structure and can be lifted into the foil surface. The fact that repeated tensile stresses or fatigue characteristics during deformation are applied in one direction.

Then, the inventors of the present invention have found that the content of Mn in the copper foil is 0.001% by mass or more, and the effect is exhibited, but in particular, when it is contained in an amount of 0.005% by mass or more, the effect is increased. The facts. Moreover, the upper limit is made 0.4 mass% for the following reasons.

As described above, in the copper foil according to the first aspect of the invention, the basic crystal axis of the unit lattice having copper is <100>, which is orthogonal to the thickness direction of the copper foil and the direction existing in the foil surface. The axis, the preferred orientation area within 15° of each azimuth difference, accounts for more than 60% of the tissue in area ratio. As a powerful means for obtaining such a structure, a method of recrystallizing agglomerated structure which is highly oriented in the thickness direction of the foil and in the direction of the roll by a direction of <100> can be formed by heat treatment of the copper foil processed by the roll. . At this time, if the concentration of the alloying element is increased, the recrystallization temperature rises. The extent varies depending on the component seed. Further, depending on the species or concentration, recrystallization may occur, but a <100> recrystallized structure and a cubic aggregate structure are not formed.

Mn is a case where the amount added in the range specified by the copper foil of the first invention is used. Although a cubic polymeric structure can be obtained, the recrystallization temperature increases as the content increases, and if it is contained in an amount exceeding 0.4% by mass, a solid cube orientation is obtained even if a heat treatment such as 500 ° C is performed. Forming will be difficult. Such a heat treatment at 500 ° C or higher is susceptible to oxidation under a simple atmosphere control, and thus it is necessary to reduce oxygen. The concentration is extremely low to carry out the heat treatment, and if a roll-to-roll type continuous heat treatment is carried out, an inflated apparatus is required, so that the manufacturing cost is increased. Therefore, in the copper foil according to the first aspect of the invention, the upper limit of the Mn content is determined by the heat treatment at 500 ° C for 1 hour, and the upper limit content of the aggregated structure defined in the present invention cannot be obtained.

Furthermore, the present invention is mainly directed to the provision of a copper foil for a flexible circuit board. Therefore, it is also possible to recrystallize the copper foil by utilizing the thermal hysteresis during the manufacturing process of the flexible circuit board, which is advantageous in terms of cost. Of course, the pre-processed and hardened copper foil may be heat-treated to form a recrystallized aggregate structure, and then the flexible circuit substrate is formed, but the resin layer is formed on the work-hardened copper foil. Handling is also easier. The method for producing the flexible circuit board includes various methods such as a casting method, a hat pressing method, and a laminating method, wherein the polyamine is coated by a casting method. The solution was subjected to heat treatment to form a resin layer made of polyimide, and the temperature was at most 400 °C. For example, in the case where the polyimide film is overlapped and subjected to thermocompression bonding to form a resin layer on the copper foil, the temperature of the thermocompression bonding is generally about 300 to 400 °C. Therefore, since the recrystallization is preferably carried out at the temperature at the time of heat treatment or thermocompression bonding, the Mn concentration in the composition of the cold rolled copper foil is more preferably not more than 0.1% by mass. In addition, if the heat treatment time is shortened, the Mn concentration of the copper foil for the flexible circuit board on the industrial scale is, for example, 0.06 mass% or less, in terms of handling treatment. . And because it can save copper foil and Juyi It is more suitable in terms of the annealing process of the copper foil before the lamination process of the amine.

On the other hand, the resistance value of copper is about 1.7 × 10 ^-8 Ω m at room temperature. In the case of being used as a flexible circuit board, the copper foil on which the wiring is formed is used for signal or power transmission, and the resistance value is preferably low. When the concentration of Mn is 0.1% by mass or more, the electrical resistance at room temperature will be 2.0 × 10 ^-8 Ω m or more, and the IACS (International Annealed Copper Standard) will be reduced to 85% or less. In this respect, the Mn concentration is more preferably not more than 0.1% by mass. Further, when the Mn concentration is 0.06 mass% or less, the resistance value is further reduced to 1.9 × 10 ^-8 Ω m or less, which is more preferable.

In the case of the copper foil according to the first aspect of the invention, the copper foil according to the first aspect of the invention may contain 0.001 mass% or more and 0.1 mass% or less of Mn, and may contain 0.005 mass. At least one of 0.2% by mass or less of Ti or 0.005 mass% or more and 2% by mass or less of Al, and having an unavoidable impurity and a residual portion of Cu. If the copper foil of such a composition is formed, the fracture ductility can be further improved to improve the fatigue characteristics. When Ti or Al is added in the above range, a small amount of Mn added in an amount of 0.001% by mass or more and 0.005% by mass or less can obtain a large effect on durability.

Here, the upper limit of the Ti content is defined by the recrystallization temperature as in the case of Mn. Ti is more effective than Mn in increasing the recrystallization temperature. However, the heat treatment at 500 ° C for 1 hour does not produce the value of the aggregated structure specified in the present invention. The upper limit of the Ti content is 0.2% by mass. Further, it is preferable that recrystallization is completed at 400 ° C or lower, and the upper limit of the Ti content at this time is preferably 0.05% by mass.

On the other hand, Al has a small effect of increasing the recrystallization temperature of copper, and although it can be added in principle to 9% by mass of the maximum solid dissolving limit of Al of copper, it is usually cast. In the case of casting solidification, if it is added in an amount of more than 2% by mass, a CuAl compound phase is easily formed. If such a compound phase is formed, when deformation is applied, the stress will concentrate in the vicinity of the CuAl compound in the copper foil, so that the fatigue characteristics are remarkably lowered.

In the copper foil according to the first aspect of the invention, in addition to Mn, Ti, and Al, unavoidable impurities are contained, but in particular, silver, iron, and nickel contained in the impurity element in the raw material copper are not described in the present invention. The effect has an effect. However, in the case of oxygen, if a large amount of oxygen is contained as copper oxide, since stress is applied to the copper foil when stress is applied to the copper foil, the oxygen content may not exceed 0.1 at the maximum. The mass % is preferably 0.05% by mass or less based on the level contained in the general tough pitch copper, and more preferably 0.001% by mass or less based on the oxygen impurity level of the oxygen-free copper.

<Copper foil relating to the second invention>

Moreover, the specification of the alloy component of the copper foil of the second invention will be described.

In order to make the copper foil highly oriented, it is preferable to accumulate and change by cold rolling. Shape, heat and recrystallize to form a cube orientation belonging to the recrystallized aggregated structure. As described above, the alloying elements have a situation in which the orientation of the cube after recrystallization is hindered, but among them, Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y, Then promote the orientation of the cube. In the case of heating under the same heat treatment conditions, Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y are compared to contain a predetermined amount of such copper and In the case where the above-mentioned alloying elements are not contained, the bulk of the cube orientation of copper may increase. In addition, alloying elements increase strength by solid solution strengthening. However, on the other hand, almost all alloying elements of copper having a face-centered cubic structure reduce the lamination defect energy to make it easy to expand the index. Therefore, it is difficult to cause cross-sliding when indexing is performed at the time of deformation, so that accumulation of localized indexing is liable to occur. As a result, it also has the effect of reducing the fatigue characteristics at the time of repeated deformation. It is found that Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb and Y are lower in effect and lower the repetitive deformation than other alloys in reducing the copper lamination defect energy. The effect of the fatigue characteristics of the time is also low.

The content of one or more alloying elements selected from the group consisting of Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y can be expressed in a small amount of addition. The effect, in particular, when it is contained in an amount of 0.005% by mass or more, the effect is increased. In addition, when these elements are added in an amount of 0.4% by mass or more based on the total amount, the degree of integration of the cube orientation is rather lowered. Moreover, since such elements are not dissolved in the copper, when a deformation is applied to the copper foil, it will occur in the vicinity of the separated phase. The stress concentration, and the stress concentration will become the starting point of the failure. If the maximum solid solution limit of the above alloying elements is 0.4% by mass or less, the value is not exceeded.

In the copper foil of the second invention, the Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y-based chemical properties are similar, and the copper foil is improved. 100> The role of orientation. Therefore, these elements may be contained by mixing two or more elements. Among them, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y are rare earth elements, and it is costly to classify each element, and there are many high prices. The metal before the element is refined and separated is referred to as a bismuth rare earth alloy (Misch metal), which is a mixture of Ce, La, Pr, and Nd as main components, and is relatively inexpensive. Since the metal contained in the rare earth alloy has the same effect, when it is added as a rare earth alloy, it is effective in cost reduction.

Although it has been described in the copper foil according to the first aspect of the invention, the present invention provides a copper foil for a flexible circuit board as a main object. Therefore, the copper foil can be recrystallized by the thermal history of the copper-clad laminate or the flexible circuit board during the manufacturing process, which is advantageous in terms of cost. Of course, it is also possible to prepare a copper-clad laminate by heat-treating the pre-processed and hardened copper foil to form a recrystallized aggregate structure, but forming a resin layer on the work-hardened copper foil, and operating it. It's easier. The method for producing the copper-clad laminate includes a casting method, a hot press method, a lamination method, and the like, and the temperature at which the resin layer is formed is also about 400 ° C, preferably at the temperature. Recrystallization of the inventive copper foil.

In the copper foil according to the second aspect of the invention, the elements other than the above may be contained as unavoidable impurities. In particular, Al, Ti (titanium), Ag, Fe, Ni, Mn (manganese), Hf (铪), Ta (钽), B (boron), or V (vanadium), as long as the copper of the second invention The effect of the present invention can be maintained within the purity of the copper foil specified in the foil (copper content). Among these elements, Al and Ti are one or more groups selected from the group consisting of Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y. When the composition of the element is more than 0.005 mass% or more and 0.2 mass% or less of Ti or at least one of 0.005 mass% or more and 0.395 mass% or less of Al, it is possible to enhance the recrystallization of the copper foil under the same conditions. The role of <100> orientation. Further, the Mg in the unavoidable impurities is chemically similar to the element group specified in the copper foil according to the second invention, but the content is preferably lowered because the degree of orientation is lowered by <100>. It is 0.001% by mass or less.

Further, among the unavoidable impurities, in the case of oxygen, if a large amount of oxygen is contained as copper oxide, since stress is concentrated on the copper oxide when stress is applied to the copper foil, the oxygen content is The content of not more than 0.1% by mass is preferably 0.05% by mass or less based on the level contained in the general tough pitch copper, and more preferably 0.001% by mass or less based on the oxygen impurity concentration level of the oxygen-free copper. Further, in terms of sulfur, the affinity with copper is also high, and it is easy to be mixed as an impurity, but the content is preferably low because of the effect of embrittlement of copper. Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, and Y which are elements specified in the copper foil according to the second invention, and Al added as needed Ti, each department and Oxygen or sulfur has a high affinity. When copper is melted for alloying, it also forms a compound with oxygen or sulfur which is harmful to the flex fatigue resistance characteristic to discharge oxygen and sulfur out of the material. Sub-secondary effect. Therefore, it is preferable that the alloying element added as described above is added in a slightly larger amount in accordance with the oxygen or sulfur content in the raw material of copper, in consideration of the portion which is removed in consideration of the preparation of the compound.

As described above, in the copper foil according to the second aspect of the invention, the contents of Ca, La, Ce, Pr, Nd, Sm, Eu, Gd, Dy, Ho, Er, Tm, Yb, Y, Al, and Ti are In the heat treatment temperature at which the resin layer is formed by a casting method, a hot press method, a lamination method, or the like to produce a copper-clad laminate, the copper foil can obtain a sufficient condition of <100> preferred orientation region. However, if the thermal history applied to the copper foil is the same, the effect of increasing the integrated body of the <100> cube orientation due to the above elements can be obtained.

<Bronze laminated board, flexible circuit board>

In the present invention, the copper foil according to the first aspect of the invention or the copper foil according to the second aspect of the invention is used, and a resin layer is laminated on the copper foil layer formed of any copper foil to form a copper-clad laminate. When the copper foil layer of the copper laminate is etched to form a predetermined wiring, a flexible circuit board excellent in flexural durability or flexibility can be obtained. The flexible circuit board is suitable for a user who forms a flexure at least one portion of the wiring, and particularly has excellent fatigue characteristics in a high deformation region in which the curvature radius of the flex portion is 2 mm or less. In order to achieve the object, in the present invention, the copper foil is formed to have the composition and component values specified in the first or second invention, and preferably, it is as follows. The constituents shown. Here, the following contents are common to the copper foils according to the first and second inventions, and the case where one of the copper foils is used is referred to as a copper-clad laminate according to the present invention, and a flexible circuit substrate. .

That is, in the present invention, in the case where high flexibility is particularly required, a copper foil for forming a wiring of a flexible circuit substrate is preferably a rolled copper foil having a thickness of 5 to 18 μm, preferably. It is preferred to use a rolled copper foil having a thickness of 9 to 12 μm. When the thickness of the rolled copper foil is 18 μm or more, it is difficult to obtain a flexible circuit board having excellent fatigue characteristics in a high deformation region having a curvature radius of 2 mm or less. Moreover, when the thickness is 5 μm or less, the handling of the copper foil and the resin layer is difficult, so that it is difficult to form a homogeneous copper-clad laminate. Furthermore, as described above, in the case of forming a copper foil layer from a rolled copper foil, a rolled copper foil may be used as a pre-heat treated, and the basic crystal axis of the unit cell of copper is <100>, which is In the thickness direction of the copper foil and the two orthogonal axes formed in a certain direction in the foil surface, the preferred orientation region within 15° of each azimuth difference can be used in an area ratio of 60% or more. The recrystallization may be formed by recrystallization in a temperature range of the above-mentioned thickness range and by a cold rolling by a resin layer formed by a casting method or a lamination method.

In the resin layer of the copper-clad laminate of the present invention, the kind of the resin forming the resin layer is not particularly limited, but may be exemplified by polyimine, polyamine, polyester, liquid crystal polymer, polyphenylene sulfide. Ether, polyether polyketone ether, and the like. Among them, polyiminoimine or liquid crystal polymer is suitable from the viewpoint of exhibiting good flexibility when forming a circuit board and having excellent heat resistance.

The thickness of the resin layer can be in accordance with the use, shape, etc. of the copper-clad laminate It is suitably set, but from the viewpoint of flexibility, it is preferably in the range of 5 to 75 μm, more preferably in the range of 9 to 50 μm, and most preferably in the range of 10 to 30 μm. When the thickness of the resin layer is less than 5 μm, the insulation reliability may be lowered. Conversely, when the thickness is 75 μm or more, when the flexible circuit board is mounted on a small-sized device or the like, the thickness of the entire circuit board may be too thick. As a result, there is also the possibility of a decrease in flexibility.

Further, in many cases, such as a small-sized device, which is mounted on a flexible circuit board, a cover material as shown in the following may be formed on the wiring formed of the copper foil layer. In this case, it is preferable to design the covering material and the resin layer in consideration of the balance of the stress applied to the wiring. According to the inventors' knowledge, for example, the polyimide resin forming the resin layer has a tensile modulus of elasticity of 4 to 6 GPa at 25 ° C and a thickness of 14 to In the range of 17 μm, the covering material used has an adhesive layer made of a thermosetting resin having a thickness of 8 to 17 μm and two layers of a polyimide layer having a thickness of 7 to 13 μm, and the adhesive layer and the poly layer It is preferable that the tensile modulus of elasticity of the entire quinone imine layer can be 2 to 4 GPa. Further, if the polyimide resin forming the resin layer has a tensile modulus of elasticity of 6 to 8 GPa at 25 ° C and a thickness of 12 to 15 μm, the covering material used has a thickness of 8 to 17 μm. The adhesive layer formed of the thermosetting resin and the polyimide layer of 7 to 13 μm in thickness, and the tensile modulus of the adhesive layer and the polyimide may be 2 to 4 GPa. .

For the method of laminating the resin layer and the copper foil layer, for example, when the resin layer is formed of polyimine, the heat can be applied to the polyimide film. The plastic polyimide or it is interposed in a manner to perform hot laminating of the copper foil (so-called lamination method). The polyimine film used in the lamination method can be exemplified by "Caboton" (Dongli DuPont (share)), "Abikar" (Zhongyuan Chemical Industry Co., Ltd.), "Yu Billex" (Ube Industries (shares)) and so on. When the polyimine film is subjected to heat-pressure bonding of the copper foil, it is preferred to allow a thermoplastic thermoplastic polyimide resin to be incorporated therein. When the polyimine film is subjected to thermocompression bonding by the lamination method to form a resin layer, the temperature of the thermocompression bonding is preferably 280 ° C or more and 400 ° C or less, preferably 300 ° C or more and 400 ° C or less.

On the other hand, from the viewpoint of easily controlling the thickness of the resin layer, the bending property, and the like, the polyimide film is coated with a polyimide solution (also called a polyaminic acid solution). dry. It is also possible to harden to form a resin layer (so-called casting method). In the casting method, the temperature for heat treatment for forming the resin layer by imidizing the polyimine precursor solution is preferably 280 ° C or higher and 400 ° C or lower, preferably 300 ° C or higher and 400 ° C or lower. It is appropriate.

The resin layer may be formed by laminating a plurality of kinds of resins, for example, a method in which two or more kinds of polyimines having different linear expansion coefficients are laminated, but in this case, heat resistance or flexibility is maintained. In view of the above, it is preferred to use an epoxy resin or the like as an adhesive, and all of the resin layers can be substantially formed from polyimine. In particular, it is preferable that the tensile modulus of the resin layer is 4 to 10 GPa, and preferably 5, in the case where it is formed of a single polyimine and the case of a plurality of polyimine. The method to 8GPa is appropriate.

In the copper-clad laminate of the present invention, it is preferred that the coefficient of linear expansion of the resin layer be in the range of 10 to 30 ppm/°C. When the resin layer is formed of a plurality of kinds of resins, the linear expansion coefficient of the entire resin layer may be such a range. In order to satisfy such a condition, for example, a low-expansion polyimine (low thermal expansion polyimide) layer having a linear expansion coefficient of 25 ppm/° C. or less, preferably 5 to 20 ppm/° C., and a resin layer formed of a layer of a high linear expandable polyimide (highly heat-expandable polyimide) having a coefficient of linear expansion of 26 ppm/° C. or more, preferably 30 to 80 ppm/° C., if such a thickness ratio is adjusted, It can be made into 10 to 30 ppm/°C. The thickness ratio of the preferred low linear expansion polyimide layer to the high linear expansion polyimide layer is in the range of 70:30 to 95:5. Further, the low-expansion polyimine layer is preferably a main resin layer of the resin layer, and the high-expansion polyimine layer is provided so as to be in contact with the copper foil. Further, the linear expansion coefficient is obtained by using a polyimine which sufficiently completes the ruthenium imidization reaction by a ruthenium imidization reaction, and using a thermo-mechanical analyser (TMA) after the temperature is raised to 250 ° C. It is cooled at a rate of 10 ° C / minute, and can be obtained from the average linear expansion coefficient in the range of 240 to 100 ° C.

Moreover, the flexible circuit board obtained from the copper-clad laminate of the present invention includes a wiring formed of a resin layer and a copper foil layer, and has a flexure portion at any position. That is to say, including the movable part in the hard disk, the hinge part of the mobile phone or the sliding part of the guide, the magnetic head of the printing machine, the optical pickup part, and the movable part of the notebook type personal computer are widely used in various electronic. In electrical equipment and the like, the circuit board itself is bent, twisted, or deformed in accordance with the action of the apparatus of the apparatus, so that the flexure is formed at any position. especially, Since the flexible circuit board of the present invention has a flexure structure excellent in flexural durability, it is suitable for sliding sliding, flexing and flexing (including side seaming) and hinge bending. The case where the bending, the bending of the guide plate, etc. are repeated, and the bending is frequent, or the miniaturization of the loaded device, the radius of curvature is 0.38 to 2.0 mm according to the bending action, and 1.25 to 2.0 mm according to the sliding deflection. In the case of a severe use condition such as a hinge flexing of 3.0 to 5.0 mm and a bending of the guide plate of 0.3 to 2.0 mm, a narrow gap of 0.3 to 1 mm and a requirement for flexibility can be severe. The use of the guide plate is particularly effective in the use of a flexing-like flexing portion having a curvature radius of 0.8 mm or less.

The width, formation, pattern, and the like of the wiring are not particularly limited, and may be appropriately designed in accordance with the use of the flexible circuit board and the mounted electronic device. In the first embodiment, the flexible circuit board used for the hinge portion of the mobile phone or the like is provided, and the wiring 2 and the connector terminal 3 formed from the resin layer 1 and the copper foil are exemplified. A schematic diagram showing a case where the flexible circuit board of Fig. 1 can be bent into a U-shape so that the flexible circuit board can be formed is shown in Fig. 2. As shown in FIG. 2, for example, when the flexible circuit board is bent into a U shape, the ridge line L is formed on the outer side (the side opposite to the inner circumference where the radius of curvature is formed). The ridge line L shown in Fig. 1 (a), Fig. 1 (b), and Fig. 2 has α° in the [100] axis direction of the preferred orientation region of the copper foil forming the copper wiring 2. angle. Here, Fig. 1(a) shows an example in which the ridge line L is formed in an inclined manner in the middle of the connector terminals 3 at both ends, but it can also be as short as in Fig. 1(b). Distance way Wiring between terminals 3. Further, in the case of a folding mobile phone or the like, in addition to the case where the position of the ridge line L of the flexing portion is fixed, it may be a manner in which the ridge line L of the flexing portion moves like a slide type mobile phone. The guide plate slides and flexes (the direction of the thick arrow shown in Fig. 1(b)). Further, the flexible circuit board of the present invention has a wiring made of a copper foil on at least one side of the resin layer, and may be formed by providing a copper foil on both surfaces of the resin layer as occasion demands.

As shown in Fig. 1, the wiring 2 formed of the copper foil of the flexible circuit board of the present invention may be oriented in any direction. °° can take any angle. That is, in the flexible circuit board of the present invention, one <100> axis of the preferred orientation region in the copper wiring is in the thickness direction of the copper foil, and is perpendicular to the resin layer 1, and other than The <100> axis can be oriented in any direction within the copper wiring plane. Further, the flexible circuit board shown in Fig. 1 is bent into a U shape so as to form a ridge line L to perform a fatigue test, and the [100] axis and flexing time in Fig. 1 Figure 1 (c) and Figure 1 (d), where the principal stresses are consistent, are the most severe directions. This is the reason as described below.

When the flexible circuit board is bent into a U shape so that the ridge line L can be formed, the main stress applied to the copper circuit differs depending on the configuration of the flexible circuit board, and the ridge line L Cutting the cross section of the copper wiring vertically, or compressive stress. For example, when the cross-sectional orientation of the wiring when the flexing portion is cut from the ridge line to the thickness direction is set to (100), the Schmitt factor of the eight slip planes (schmidt) when it is flexed Will become equivalent and 8 The sliding system acts at the same time, so that the indexing is easy to accumulate locally. As shown in Fig. 1 (a) or (b), when the angle formed by the [100] axis and the ridge line L is made to an angle other than 90°, it is made up of 8 {111} of the sliding surface of the copper foil. The largest main sliding surface of the Schmitt factor becomes four, and the shearing slip becomes good, so that localized work hardening is less likely to occur.

In the well-known rolled copper foil used in the prior art, the long-distance direction of the copper foil corresponds to the rolling direction, as shown in Fig. 1 (c) or (d), usually along its main orientation <100>. To form a circuit. Further, when a circuit is formed in such a direction by using a copper foil which is used, there is a problem in durability. In contrast, in the present invention, even in such a case, it is difficult to cause cracking for repetitive flexing. Of course, when a copper foil wiring is formed as shown in Fig. 1 (a) or (b), it becomes a flexible circuit board having higher flexural fatigue characteristics.

As described above, since the copper foil of the present invention is highly oriented and contains a predetermined alloy composition, it is difficult to cause metal fatigue and excellent durability against stress and deformation. Moreover, since such a copper foil is used to form a copper-clad laminate, and the copper foil is etched by a known method to form a flexible circuit board obtained by wiring, it is possible to have a repeating of the bending or a small curvature radius. The strength is still durable and is superior to the flexibility, so that the design of the flexible circuit board in consideration of the shape of the wiring of the flexure portion or the like is not limited.

[Examples]

Hereinafter, the contents of the present invention will be more specifically described based on examples and comparative examples. Hereinafter, the examples of the present invention are shown, and the present invention is not limited by the examples. In the present embodiment, a copper foil having various alloying elements was produced, and the copper foil structure was analyzed from the test single-sided copper-clad laminate obtained by using the copper foil, and the test was performed from the test single-sided copper-clad laminate. A flexible circuit board was used to measure the flexural fatigue characteristics.

[Example 1]

In the present embodiment, a copper foil having Mn as an alloying element was produced, and the test for cracking ductility was measured from the copper-clad laminate for testing using the copper foil, and the test was performed from the single-sided copper-clad laminate for the test. A flexible circuit board to measure flex fatigue characteristics.

The copper foils of the sample numbers 1 to 16 used in the present embodiment were produced in the following manner. An oxygen-free copper having a purity of 99.99% and an oxygen content of 0.0008% and Mn having a purity of 99.9% as measured in Table 1 were melted and stirred in a graphite crucible under an argon atmosphere, and then cast. Casting in a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm to make an ingot. Then, in the wide direction, tentering rolling can be performed to a thickness of 10 mm, hot rolling can be performed at a maximum temperature of 600 ° C, and thickness can be 2 mm in the longitudinal direction. Hot rolling is carried out. Then, cold rolling was performed to a thickness of 9 μm. Among them, slit processing was used at a thickness of 0.5 mm to cut both ends, and the width was aligned to 60 mm. Thus, the resulting copper foil is wide The width is 60mm and the thickness is 9μm.

Then, a part of the copper foil was subjected to recrystallization heat treatment at 500 ° C for 1 hour in a vacuum furnace. As a result of chemical analysis of the Mn concentrations at both ends and the central portion of the obtained copper foil, it was confirmed whether or not the copper foil was subjected to recrystallization heat treatment without any concentration deviation caused by the location.

Further, the polyamic acid solution of the precursor of the polyimine which constitutes the resin layer of the flexible circuit board for a test of Example 1 was synthesized in the following manner.

(Synthesis Example 1)

N,N-dimethylacetamide was placed in a reaction vessel capable of introducing nitrogen while having a thermocouple and a stirrer. In this reaction vessel, 2,2-bis[4-(4-aminophenoxy)phenyl]propane (BAPP) was dissolved in a vessel while stirring. Next, pyromellitic dianhydride (PMDA) was added. It can be placed in such a manner that the total amount of the monomers to be placed can be 15% by mass. Then, stirring was continued for 3 hours to obtain a resin solution of polyamic acid a. The solution viscosity of the polyacetic acid a resin solution was 3,000 cps (centipoise).

(Synthesis Example 2)

N,N-dimethylacetamide was placed in a reaction vessel capable of introducing nitrogen while having a thermocouple and a stirrer. Into this reaction vessel, 2,2'-dimethyl-4,4'-diaminobiphenyl (m-TB) was placed. Next, 3,3'4,4'-diphenyltetracarboxylic dianhydride (BPDA) and pyromellitic dianhydride (BPDA) and pyromellitic dianhydride (BPDA) were added. PMDA). The total amount of the monomers to be incorporated can be 15% by mass, and the molar ratio of each of the acid anhydrides (BPDA: PMDA) can be set to 20:80. Then, stirring was continued for 3 hours to obtain a resin solution of polylysine b. The solution viscosity of the polyacetic acid b resin solution was 20,000 cps.

Next, a method of forming a copper-clad laminate of a composite of copper foil and polyimine will be described.

On the surface of the copper foil of the sample Nos. 1 to 16 prepared in the above, the polyamic acid solution a prepared in the above was applied and dried (after hardening, a thermoplastic polyimide having a film thickness of 2 μm was formed). An amine), and coated with poly-proline acid b, and dried (after hardening, a low thermal expansion polyimine having a film thickness of 9 μm is formed), and then polyacrylic acid a is coated thereon and It is dried (after curing, a thermoplastic polyimide having a film thickness of 2 μm is formed), and the maximum temperature is taken as 400 ° C, and the heating time under the heating condition of a temperature range of 360 to 400 ° C is 5 minutes. A resin layer formed of a polylayer of a 3-layer structure is formed.

Then, it was cut into a length of 250 mm along the rolling direction (MD (longitudinal) direction) of the copper foil, and cut into a rectangular shape having a width of 40 mm in a direction orthogonal to the rolling direction (TD (lateral) direction). A test single-sided copper-clad laminate having a resin layer (polyimine) 1 having a thickness of 13 μm and a copper foil layer 2 having a thickness of 9 μm was obtained (Fig. 5). The tensile modulus of elasticity of the entire resin layer at this time was 7.5 GPa.

The copper foil (copper foil layer) in the single-sided copper-clad laminate for the test obtained above was subjected to crack ductility and texture analysis.

The fracture and ductility of copper foil is the use of a single-sided copper laminate for testing. The copper foil obtained by chemically removing the resin layer formed by the polyimide reaction has a length of 150 mm in the rolling direction, and is cut into a width of 10 mm in the direction perpendicular to the rolling direction in the foil surface. The length direction was measured in accordance with the conditions of a distance between the punctuation of 100 mm and a rate of extension of 10 mm/min. At the time of measurement, seven samples were prepared for each type of copper foil to determine the average value of the fracture ductility.

The structure of the copper foil was obtained by using a colloidal silica on the rolled surface of each copper foil, mechanically and chemically polished, and then performing orientation analysis using an EBSD apparatus. The apparatus used was an FE-SEM (S-4100) manufactured by Hitachi, Ltd., an EBSD device manufactured by TSL, and a software (OIM Analysis 5.2). The measurement area was a region of about 800 μm × 1600 μm, and an acceleration voltage of 20 kV and a measurement step interval of 4 μm were measured. That is, the number of measurement points is 80000 points. The degree of integration of the cubic aggregated structure of the present invention, that is, the evaluation of the preferred orientation area of <100>, can be measured in the thickness direction of the foil and the rolling direction of the foil, and <100> enters the measurement point within 15°. The ratio of all measurement points is expressed. The number of measurements was carried out on five samples with different individual varieties, and the percentage of the decimal point was rounded off. Further, using the obtained data, the orientation difference of the adjacent crystal grains was 15 or more as a grain boundary to evaluate the grain diameter.

Next, a predetermined mask was applied to the copper foil layer side of the test single-sided copper-clad laminate obtained in the above, and a chloride/copper chloride-based solution was used for etching, and line width was used. ) (1) is 150 μm The wiring direction of the linear wiring can be parallel to the rolling direction, and the wiring pattern can be formed so that the space width can be 250 μm. Then, in accordance with JIS 6471, it is possible to obtain 150 mm in the long-distance direction along the wiring direction H of the circuit board, and to be perpendicular to the wiring direction H, in accordance with the sample for the flexural test which will be described later. A test flexible circuit board having a width of 40 mm. It was confirmed that there was no change in the structure of the copper foil before and after the formation by the etching circuit.

The MIT flexural test was carried out by using the flexible circuit board for the test obtained above and in accordance with JIS C5016. The mode diagram of the test is shown in Figure 3. The device is manufactured by Toyo Seiki Co., Ltd. (STROGRAPH-R1), and one end of the long-distance direction of the test flexible circuit board is fixed to the chuck frame of the flexure test device, and the other end is fixed by the weight to the chuck. The center is rotated by 135±5 degrees per revolution depending on the vibration speed of 150 times/min, and is flexed so that the radius of curvature can be 0.8 mm, and the conduction of the wiring of the circuit board is blocked. The number of times is obtained as the number of flexings.

In this test condition, since the ridge line formed by the flexure portion bends the wiring direction H of the wiring of the test flexible circuit substrate in an orthogonal manner, the principal stress and the main deformation applied to the copper circuit Then, it is a tensile stress and a tensile deformation parallel to the rolling direction. After observing the circuit from the thickness direction of the copper foil after the flexural test, it was confirmed that the crack occurred in the vicinity of the ridge line of the flexing portion and the wire was slightly perpendicular to the rolling direction.

The amount of Mn in the copper foil obtained by the above test, the fracture ductility of the copper foil, the <100> preferred orientation area ratio, and the flex life are expressed in in FIG. 1. The flex life is an average value of the results of five test flexible circuit boards prepared for each type of copper foil.

As is known from Table 1, the fatigue resistance of the fatigue life of 2000 times or more can be obtained, and the Mn concentration is 0.001% by mass or more and 0.4% by mass or less, and the <100> preferred orientation region is The fact that the area ratio is above 60%. When the concentration of Mn is 0.02% by mass or less, a cubic aggregate structure having an extremely high degree of bulk is obtained regardless of the presence or absence of recrystallization heat treatment at 500 ° C for 1 hour. In this range, there is no unrecognized intentional difference in the degree of the bulk, and as the Mn concentration increases, the fatigue life increases, and particularly at 0.005 mass% or more, good flex resistance characteristics are obtained. This is due to the addition of Mn, and when it is flexed The length direction of the wiring in the direction of the principal stress, that is, the crack-breaking property in the rolling direction is increased. When the sample having a Mn concentration of 0.001% by mass or more is found, the crystal grains having a cubic orientation are developed to have a size of 800 μm or more in the surface of the copper foil so as to penetrate through the thickness direction of the foil.

When the sample numbers 11 and 12 having a Mn concentration of 0.1% by mass were compared, the sample of the test No. 11 had a high flex resistance characteristic, and the number of samples of the sample No. 12 was relatively small. This is because the copper foil of the sample of the sample No. 11 was recrystallized by the recrystallization heat treatment at 500 ° C for 1 hour, and the area ratio of the <100> preferred orientation region was large. Further, in the sample having a Mn concentration of 0.42% by mass or more, the recrystallization heat treatment is applied before the formation of the flexible circuit board, but the area ratio of the <100> preferred orientation region is 60% or less, and the crack is broken. The number of flexing is also greatly reduced. This is due to the excessive addition of Mn and the increase in recrystallization temperature.

The formation time of the polyimine in this example was 5 minutes, which was a test for continuous production of a roll to a roller. When the sample which has not been subjected to the recrystallization heat treatment at 500 ° C for 1 hour beforehand is compared, when the Mn concentration is 0.005 mass% or more and 0.06 mass% or less, the flexural life is increased. In other words, a copper foil of such a concentration range is particularly suitable as a copper foil used in the production of a polyimide substrate having a resin layer made of polyimide.

[Example 2]

In the present embodiment, Mn, Ti, and Al are used as alloying elements. A copper foil for a test, a test flexible circuit board was prepared from the test single-sided copper-clad laminate, and the flexural ductility was measured from the test single-sided copper-clad laminate using the copper foil. Fatigue properties.

The copper foils of the sample numbers 17 to 38 used in the present embodiment were produced in the following manner. The toughness copper having a purity of 99.9% and an oxygen content of 0.015% and Mn, Ti, and Al each having a purity of 99.9% as measured by a predetermined amount are as shown in Table 2, and argon gas is present in the graphite crucible. After melting and stirring in an atmosphere, it was cast in a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm to prepare an ingot. Then, tenter rolling was carried out so as to have a thickness of 10 mm in the width direction, hot rolling was performed at a maximum of 600 ° C, and hot rolling was carried out under the same conditions in the longitudinal direction so as to have a thickness of 2 mm. Then, cold rolling was performed to a thickness of 9 μm. Among them, the strip was cut at a thickness of 0.5 mm to cut both ends, and the width was aligned to 60 mm. Therefore, the obtained copper foil was a width of 60 mm and a thickness of 12 μm.

Then, a part of the copper foil was subjected to recrystallization heat treatment at 500 ° C for 1 hour in a vacuum furnace. As a result of chemical analysis of the concentrations of Mn, Ti, and Al at both ends and the central portion of the obtained copper foil, it was confirmed whether or not the copper foil was subjected to recrystallization heat treatment without any concentration deviation caused by the cause.

Next, a polylysine solution prepared in the same manner as in Synthesis Example 1 and Synthesis Example 2 of Example 1 was used, and the surface of the copper foil of the sample Nos. 17 to 38 prepared in the above was first coated. The polyaminic acid solution a is dried (after curing, a thermoplastic polyimide having a film thickness of 2 μm is formed), and the poly-proline b is coated thereon and dried (curing to form a film) a low thermal expansion polyimine having a thickness of 8 μm, and then coating the polyamid acid a thereon and drying it (after curing, a thermoplastic polyimide having a film thickness of 2 μm is formed), and the maximum temperature is 400 ° C. The accumulation time under the temperature range of 360 ° C to 400 ° C was heat-treated under heating conditions of 5 minutes to form a resin layer made of a polylayer of a three-layer structure.

Then, it was cut so as to have a length of 250 mm along the rolling direction of the copper foil and a rectangular shape having a width of 40 mm in the direction perpendicular to the rolling direction, thereby obtaining a resin layer (polyimine) having a thickness of 12 μm and A single-sided copper-clad laminate for testing of Example 2 of a copper foil layer having a thickness of 12 μm.

The copper foil (copper foil layer) in the single-sided copper-clad laminate for the test obtained above was subjected to crack ductility and texture analysis in the same manner as in Example 1. In addition, a predetermined mask was coated on the side of the copper foil layer of the test single-sided copper-clad laminate, and etching was performed using a ferric chloride/copper chloride-based solution to form the same wiring pattern as in the first embodiment. Then, in the direction of the wiring direction H of the circuit board, it is 150 mm in the long-distance direction and orthogonal to the wiring direction H, in accordance with JIS 6471, which can also serve as a sample for the flexural test described later. A test flexible circuit board having a width of 40 mm. Here, the fact that the structure of the copper foil did not change before and after the formation by the circuit for etching was confirmed.

Next, as for the test flexible circuit board having the resin layer 1 and the wiring (copper foil) 2, as shown in FIG. 4(b), epoxy-based adhesive was used on the surface of each wiring pattern side. The adhesive was laminated to cover material 7 (CVK-0515KA manufactured by Ozawa Seisakusho Co., Ltd.: thickness: 12.5 μm). Made of adhesive The thickness of the adhesive layer 6 is 15 μm in the portion of the copper-free foil circuit and 6 μm in the portion where the copper foil circuit is present. Further, it was cut to 15 mm in the long-distance direction along the wiring direction (H direction), and cut to a width of 8 mm in the direction orthogonal to the wiring direction, thereby obtaining test flexibility for use as an IPC test sample. Circuit board.

The IPC test, as shown in the pattern diagram in Fig. 4, is a test for simulating a slide flex as a kind of flexing form used for a mobile phone or the like. In the IPC test, as shown in Fig. 4, the flexing portion is set according to the determined gap length 8, and the one side is fixed by the fixing portion 9, so that the slide moving part 10 on the opposite side is placed. The method of the figure is repeated to test the back and forth movement. Thus, in the region of the stroke amount of the portion that moves it back and forth, the substrate will receive repeated flexing. In the present embodiment, the resin layer (polyimine) 1 was formed as the outer side, the gap length was made 1 mm, that is, the flexural radius was made 0.5 mm, and the stroke was made 38 mm to perform repeated sliding to carry out the test. . In the test, the electrical resistance of the circuit of the test flexible circuit board was measured, and the degree of progress of the fatigue crack of the copper foil circuit due to the increase in resistance was monitored. In the present embodiment, the number of strokes in which the resistance of the circuit reaches twice the initial value is taken as the circuit breaking life. In this test condition, the ridge line formed in the flexure portion is subjected to flexing so that the wiring direction of the wiring 2 of the test flexible circuit board is orthogonal to each other, and the principal stress applied to the copper foil circuit is mainly When the deformation is performed, the tensile stress and the tensile deformation are parallel to the rolling direction.

In the case of the copper foil after the cracking life of the circuit, a scanning electron microscope was used to observe the cross section of the copper foil cut in the thickness direction so as to be orthogonal to the sliding direction, and it was observed that although there was a degree of difference However, cracks occur on the surface of each of the copper foils on the side of the resin layer and the side of the covering material, and in particular, a large number of cracks are introduced into the surface of the copper foil on the side of the resin layer on the outer side of the flexing portion.

The results of the Mn, Ti, and Al in the copper foil obtained by the above test, the fracture ductility of the copper foil, the <100> preferred orientation area ratio, and the flex life were shown in Table 2.

As can be seen from Table 2, the reason why the fatigue life can exceed 30,000 times in the IPC test is that the Mn concentration is 0.001% by mass or more, and the Ti concentration is 0.005% by mass or more and 0.2% by mass or less. Or the fact that the Al concentration is 0.005 mass% or more and 2 mass% or less, and the area ratio of the <100> preferred orientation region is 60% or more. When the Ti concentration or the Al concentration is 0.2% by mass or more and 2% by mass or more, even after the recrystallization heat treatment at 500 ° C for 1 hour, a cubic focusing structure having an extremely high degree of bulk is not obtained. The sample has low flex resistance. When the structure of the sample belonging to sample No. 31 having an Al concentration of 2.1% by mass after the end of the IPC test was observed, it was found that an intermetallic compound composed of Cu and Al was present, and cracks occurred in the vicinity. The reason why the fatigue life is lowered is that a solvent cannot be formed into a single phase according to a usual solvent, so that an intermetallic compound is formed around an intermetallic compound which is harder than copper.

In addition to Mn, the addition of a predetermined amount of Ti or Al results in an increase in the fracture ductility. In particular, in the case where Mn is added separately, a large effect is obtained with a low Mn concentration. Further, in addition to Mn, when both Ti and Al were added, the fatigue life was greatly improved in the IPC flexural test.

[Example 3]

The copper foil used in the present embodiment was produced as follows. As the raw material, oxygen-free copper having a thickness of 15 mm, a purity of 99.99% or more and an oxygen content of 0.0008% was used. The raw material copper and the energy can be set to a predetermined concentration Each of the alloying elements weighed in the manner was melted and stirred in a graphite crucible in an argon atmosphere, and then cast in a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm to prepare an ingot. Among the alloy elements, the purity of yttrium (Y), calcium (Ca), and yttrium (Yb) is 99.9% or more. Further, as the alloying element, a cerium rare earth alloy (Misch metal) is also used. The main component of the lanthanum rare earth alloy is such that La (镧) is 25% by mass, Ce (铈) is 53% by mass, Pr (鐠) is 6% by mass, and Nd (钕) is 15% by mass, and these elements are aggregated. The purity is 99% by mass, and the remainder is other unavoidable impurities containing other rare earth metals.

The ingot to be cast is subjected to tenter rolling in a wide direction so as to have a thickness of 10 mm, and hot rolling is performed at a maximum of 600 ° C, and the same condition can be obtained by a thickness of 1.5 mm in the longitudinal direction. Hot rolling is carried out. A sample in which no alloying elements were added. Then, the raw material copper plate is cut to the same size as the cast ingot as it is, and hot rolled under the same conditions. Then, these hot rolled sheets were pressed to a thickness of 9 μm, and cold rolling was performed. Among them, the strip was cut at a thickness of 0.5 mm to cut both ends, and the width was aligned to 60 mm. Therefore, the obtained copper foil was a width of 60 mm and a thickness of 9 μm. Further, melting and casting were carried out without adding an alloying element to prepare a comparative material produced in the same manufacturing process. The chemical analysis of the alloy element concentrations at both ends and the center portion of the obtained copper foil confirmed the fact that the concentration deviation caused by the defect was not observed. The alloy concentrations of the copper foils (sample numbers 39 to 70) used in the examples are collectively shown in Table 3. In Table 3, the content of copper is calculated from the alloy element analyzed and the amount of impurities derived from the raw material, as calculated in the following manner. The scope of the theory.

That is, the lower limit of the copper content shown in Table 3 is obtained from "(minimum value of raw material purity) - (alloy element content) - (impurity derived from alloying elements)". For example, in the case of sample number 41, it is "99.99-0.0042-0.0042 x 1999=99.9858 (%)", and in the case of sample number 61, it is "99.99-(0.0026+0.0012+0.0002+0.005)-(0.0026+0.0012) +0.0002+0.005)×1/99=99.9854”. On the other hand, the upper limit is obtained from "100-(alloy element content)". When such an upper limit value is calculated, an impurity derived from an alloying element is treated as a gas component refined in the alloying process, and is not included in the calculation formula. For example, in the case of sample number 41, it is "100-0.0042 = 99.9958 (%)". However, in the case where the copper foil of the alloying element is not added as in the sample numbers 39 and 40, the oxygen content is reduced. Further, if the numerical value of the fifth or lower decimal point occurs, the lower limit value is calculated by subtracting the fifth or lower decimal point.

Moreover, the polyamic acid solution which is a precursor of the polyimide of the resin layer of the test flexible circuit board of this Example was obtained by the two synthesis examples described in Example 1.

Next, a method of forming a copper-clad laminate which is a composite of copper foil and polyimine will be described.

The one side surface of the copper foil prepared above was applied to the polyamic acid solution a obtained in Synthesis Example 1 and dried (after curing, a thermoplastic polyimide having a film thickness of 2 μm was formed), and was coated thereon. The polylysine b obtained in Synthesis Example 2 was dried and dried (after hardening, a low thermal expansion of a film thickness of 9 μm was formed). Polyimine), which is coated with polylysine a and dried (hardened to form a thermoplastic polyimide having a film thickness of 2 μm) and passed through a temperature of 280 ° C or 350 ° C in cumulative time. It can be heated under the conditions of 5 minutes or more to form a resin layer made of a polylayer of a three-layer structure. Here, the heat treatment temperature is set to a polyamidene formation temperature.

Then, it was cut into a length of 250 mm along the rolling direction (MD direction) of the copper foil, and the direction orthogonal to the rolling direction (TD direction) was cut into a rectangular shape having a width of 40 mm to obtain a resin having a thickness of 13 μm. A single-sided copper-clad laminate for testing of a layer (polyimine) 1 and a copper foil layer 2 having a thickness of 9 μm (Fig. 5). The tensile modulus of elasticity of the entire resin layer at this time was 7.5 GPa.

The structure analysis was carried out in the same manner as in Example 1 on the copper foil (copper foil layer) in the single-sided copper-clad laminate obtained above. Moreover, the copper foil layer side of the test single-sided copper-clad laminate obtained above was covered with a predetermined mask, and etching was performed using a ferric chloride/copper chloride-based solution to form the same wiring pattern as in the first embodiment. . Then, in accordance with JIS 6471, it can be made to have a diameter of 150 mm in the long-distance direction along the wiring direction H of the circuit board, and is wide in the direction orthogonal to the wiring direction H. A 40 mm test flexible circuit board. It was confirmed that there was no change in the structure of the copper foil before and after the formation by the etching circuit.

The MIT flexural test was carried out in the same manner as in Example 1 using the flexible circuit board for the test obtained above. In this test condition, the ridge line formed by the flexure portion is subjected to flexion in a manner orthogonal to the wiring direction H of the wiring of the test flexible circuit substrate. The principal stress and the main deformation applied to the copper foil circuit are tensile stress and tensile deformation parallel to the rolling direction. When the circuit was observed from the thickness direction of the copper foil after the flexural test, it was confirmed that cracks occurred in the vicinity of the ridge line of the flexing portion in a direction perpendicular to the rolling direction, and the wire was broken.

Table 3 shows the amount of alloying elements in the copper foil obtained by the above test, the <100> preferred orientation area ratio, and the flex life, together with the sample number and the polyimine forming temperature. The flex life is an average of the results of five test flexible circuit boards prepared for each copper foil. Among the component values, the (-) mark indicates the fact that the chemical analysis is below the measurement limit value.

From the results shown in Table 3, it is understood that the copper foil produced by adding no alloying elements is at least one of a group selected from the group consisting of Ca, La, Ce, Pr, Nd, Yb, and Y, and is 0.005 mass. When the amount of % or more of 0.4% by mass or less is contained and compared with the same heat treatment temperature, it is found that the area ratio of the <100> preferred orientation region is increased, and the fatigue life is improved. In addition to Ca or Y, La having a large metal radius and a minimum Yb in the lanthanoid genus are also effective, and can be judged to have similar chemical characteristics and have an intermediate metal radius. Sm (钐), Eu (铕), Gd (釓), Dy (镝), Ho (鈥), Er (铒), and Tm (銩) have the same effect.

Moreover, it is known that the area ratio of the <100> preferred orientation region of the copper foil is largely different due to the temperature at which the single-sided copper-clad laminate for the test is formed, that is, the temperature at which the polyimide is formed in the present embodiment. However, at 280 ° C, in the thermal history of 5 minutes, within the range of the above-mentioned alloy composition, the area ratio of the <100> preferred orientation region is more than 60%, and the copper foil is produced without adding the alloying element. The fact that the area ratio and fatigue life of the preferred orientation area are excellent for <100>. Further, in the case where 0.4% by mass of Ca is added to the sample numbers 52 to 54, (for example, sample number 54), the reason why the area ratio of the <100> preferred orientation region is lowered may be increased by the addition of alloying elements. The recrystallization temperature is such that the formation of the <100> recrystallized aggregated structure is hindered.

[Example 4]

In this embodiment, a rare earth alloy, Ti, and Al are used. A copper foil having such an alloy element was produced, and the copper foil structure was analyzed from the test single-sided copper-clad laminate obtained by using the copper foil, and the test was performed from the test single-sided copper-clad laminate. A flexible circuit board to measure flex fatigue characteristics. Here, the main components of the lanthanum rare earth alloy used in the present embodiment are La of 25% by mass, Ce of 54% by mass, Pr of 6% by mass, and Nd of 14% by mass, and the sum of these is 99% by mass. In addition, the constituents are other inevitable impurities containing other rare earth metals.

The copper foil used in the present embodiment was produced as follows. An electrolytic copper plate having a thickness of 15 mm, a purity of 99.9% or more, an oxygen content of 0.015 mass%, a sulfur content of 0.03 mass%, and a silver content of 0.02 mass%, and a purity of 99.9% or more. Ti and an Al alloy element, and a rare earth alloy having the above-mentioned constituent elements and their purity are weighed so as to have a predetermined concentration, and then melted and stirred in a graphite crucible in an argon atmosphere, and then cast in a width. An ingot was produced in a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm.

The cast ingot is subjected to tenter rolling in a width direction of 10 mm, and is subjected to hot rolling at a maximum temperature of 600 ° C, and then subjected to the same conditions in a length direction of 1 mm. Hot rolling. Then, cold rolling was performed to a thickness of 12 μm. Among them, the strip was cut at a thickness of 0.5 mm to cut both ends, and the width was aligned to 60 mm. Therefore, the obtained copper foil was a width of 60 mm and a thickness of 12 μm. In addition, it is melted and cast without adding an alloying element, and the same is produced. Comparative materials made during the manufacturing process. Further, as a result of chemical analysis of the concentration of the alloy component in the obtained copper foil, it was confirmed that the concentration deviation caused by the defect was not observed. The alloy concentrations of the copper foils (sample numbers 71 to 84) used in the present examples are collectively shown in Table 4. In Table 4, the content of copper, as explained in Example 3, is calculated from the amount of impurities of the alloy element and the raw material analyzed, and is in the theoretical range.

In this case, the upper limit of the copper content is calculated by the fact that the impurity other than the impurity is a gas component, and is completely discharged outside the system due to the reaction with the gas or the rare earth element during the alloying process. .

On the other hand, the lower limit is calculated as the amount of impurities in the raw material remaining in the alloy. In other words, the alloy element content other than silver is removed from the lower limit of the purity of the raw material copper, and 1% other than La, Ce, Pr, and Nd in the rare earth element are other than the elements shown in Table 4. Those who have made all of these residues, and subtracted 0.1% of the impurities of Al and Ti in the same manner. Here, silver is not added as an alloying element, but is mainly a mixture of raw material copper as an impurity, and is added to the deducted value. For example, the lower limit of sample number 72 will be "99.9-(0.053+0.024+0.0061+0.014+0.0042)-1/99×(0.053+0.024+0.0061+0.014)-1/999×0.0042+0.018=99.8147 "."

Next, the polyamic acid solution a prepared in the same manner as in Synthesis Example 1 of Example 1 was applied and dried (after hardening, a thermoplastic polyimide having a film thickness of 2 μm was formed), and coated thereon. Polylysine b prepared in the same manner as in Synthesis Example 2 of Example 1 and dried (hardened) Filming a low thermal expansion polyimine with a thickness of 8 μm, and then coating the polyamid acid a thereon and drying it (after curing, a thermoplastic polyimide having a film thickness of 2 μm is formed), and the maximum temperature is 320 ° C. The temperature of the polyimine layer (resin layer) can be formed by applying a heating condition of 10 minutes in an accumulated time.

Then, it was cut into a length of 250 mm in the rolling direction (MD direction) along the copper foil, and cut into a rectangular shape having a width of 40 mm in a direction orthogonal to the rolling direction (TD direction) to obtain a polymer having a thickness of 12 μm. A single-sided copper-clad laminate for testing according to Example 2 of the yttrium imide layer (resin layer) 1 and the copper foil layer 2 having a thickness of 12 μm (Fig. 5). The tensile modulus of elasticity of the entire resin layer at this time was 7.5 GPa.

The structure analysis was carried out in the same manner as in Example 1 on the copper foil (copper foil layer) in the single-sided copper-clad laminate obtained above. Moreover, a predetermined mask was coated on the side of the copper foil layer of the test single-sided copper-clad laminate, and etching was performed using a ferric chloride/copper chloride-based solution to form a wiring pattern similar to that of the first embodiment. Then, in the direction of the wiring direction H of the circuit board, it is 150 mm in the long-distance direction and orthogonal to the wiring direction H, in accordance with JIS 6471, which can also serve as a sample for the flexural test described later. A test flexible circuit board having a width of 40 mm. Here, the fact that the structure of the copper foil did not change before and after the formation by the circuit for etching was confirmed.

Next, as for the test flexible circuit board having the resin layer 1 and the wiring (copper foil) 2, as shown in FIG. 4(b), epoxy-based adhesive was used on the surface of each wiring pattern side. The adhesive was laminated to cover material 7 (CVK-0515KA manufactured by Ozawa Seisakusho Co., Ltd.: thickness: 12.5 μm). The thickness of the adhesive layer 6 formed by the adhesive is 15 μm in the portion of the copper-free foil circuit. In the part with the copper foil circuit, it is 6 μm. Further, it was cut to 15 mm in the long-distance direction along the wiring direction (H direction), and was cut to a width of 8 mm in the direction orthogonal to the wiring direction, thereby obtaining test flexibility for use as an IPC test sample. Circuit board. Then, the IPC test was carried out in the same manner as in Example 2, and the number of strokes in which the resistance of the circuit reached twice the initial value was obtained as the circuit breaking life. In the same manner as in the second embodiment, the copper foil after the circuit breaking life was observed by using a scanning electron microscope to observe the cross section of the copper foil in the thickness direction so as to be orthogonal to the sliding direction. Although there is a degree of difference, cracks occur on the surface of each of the copper foils on the side of the resin layer and the side of the covering material, and in particular, a large number of cracks are introduced into the surface of the copper foil on the side of the resin layer on the outer side of the flexing portion.

Table 4 shows the alloy component values, the <100> preferred orientation area ratio, and the flex life, which are obtained from the copper foil obtained by the above test, together with the sample number and the polyimide temperature. Among the component values, the (-) mark indicates the fact that the chemical analysis is below the measurement limit value. Since the raw material copper used in the present embodiment has a relatively low purity, a large amount of Ag is detected in the copper foil in addition to the alloying elements added. Further, oxygen and sulfur were detected in addition to the unavoidable impurities.

It can be seen from the results shown in Table 4 that, compared with the case where no alloying elements are added at all, the area ratio of the <100> preferred orientation region of the copper foil and the dependence of the rare earth alloy or alloying elements are found. The fact that the fatigue life measured by the IPC test is increased. Further, when the alloys having the same alloy concentration of Ce, La, Pr, and Nd are the same, it is found that when Al, Ti, or both of them are added, when the concentration is increased within the range specified by the present invention, Increase the area ratio of the <100> preferred orientation area and the fatigue life measured by the IPC test. However, the sample to which the sample No. 76 of 0.41% by mass of Al and the sample No. 81 to which Ti is added in an amount of 0.21% by mass were used to reduce the fatigue life. It may be due to the addition of excess alloying elements, which increases the recrystallization temperature so that the formation of <100> recrystallized aggregated structure is impaired.

[Example 5]

In the present embodiment, Ce, La, Y, Sm, Ca, and Al were used as alloying elements to prepare such copper alloy foils, and copper foil was used for the test single-sided copper-clad laminate obtained by using the alloy foil. At the same time as the analysis of the structure, a flexible circuit board for testing was fabricated from a single-sided copper-clad laminate for testing to measure the flexural fatigue characteristics. Here, the purity of the alloying elements used in the present embodiment is 99.9% or more, and each has a granular shape of 2 to 3 mm.

The copper foil used in the present embodiment was produced as follows. The raw material copper is a tough pitch copper having a diameter of 5 mm and a length of about 20 mm, and has a purity of 99.96% and an oxygen content of 0.029% by mass. Again, the alloying elements are before melting The feed composition (quantity composition) fed was fixed at 0.01%. That is, the sample No. 89 shown in Table 5 below was 99.8% of raw material copper, 0.1% of Ce, and 0.1% of Al.

The melting and casting of raw material copper and alloying elements are carried out by the following two methods.

In the first type, the alloying element encapsulated in the copper foil obtained by rolling the raw material copper is placed in the crucible, and after first evacuating in a vacuum furnace, 99.99% of argon gas is introduced, and the pressure is controlled to 1 atmosphere. In an argon atmosphere, after melting at 1200 ° C and stirring, it was cast in a furnace of a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm to prepare an ingot. The ingot produced was ultrasonically washed in an acid washing solution in which 20% hydrochloric acid and 0.1% hydrogen peroxide water were added to pure water to remove the scale of the surface.

In the second type, the alloying element encapsulated in the copper foil rolled by the raw material copper is placed in a crucible, and after being melted into 1200 ° C under the introduction of 99.99% of argon gas in the box furnace, the crucible is taken out and exposed to the atmosphere. The ingot was cast in a rectangular parallelepiped graphite mold having a width of 50 mm, a length of 100 mm, and a thickness of 15 mm. The ingot produced was ultrasonically washed in an acid washing solution containing 20% hydrochloric acid and 0.1% hydrogen peroxide water in pure water to remove dirt on the surface.

The processing method of the ingot afterwards is not the same as the atmosphere at the time of casting as described above, and the same conditions are all made. The ingot is subjected to tenter rolling in a width direction of 10 mm, and is subjected to hot rolling at a maximum of 600 ° C, and then to a length of 1 mm in the longitudinal direction. The conditions were subjected to hot rolling. Then, cold rolling was performed to a thickness of 12 μm. Among them, the strip was cut at a thickness of 0.5 mm to cut both ends, and the width was aligned to 60 mm. Therefore, the obtained copper foil was a width of 60 mm and a thickness of 12 μm. Further, melting and casting were carried out without adding an alloying element to prepare a comparative material produced in the same manufacturing process. Further, as a result of chemical analysis of the concentration of the alloy component in the obtained copper foil, it was confirmed that the concentration deviation caused by the defect was not observed. The alloy concentrations of the copper foils (sample numbers 85 to 98) used in the examples are collectively shown in Table 5.

In Table 5, the copper content is a calculated value from the amount of impurities of the element and the raw material analyzed, and is a theoretical range. The upper limit of the copper content is calculated as being composed only of the alloying elements in the table and oxygen and copper. Therefore, for example, in the case of the sample number 89, the upper limit value is "100-0.079-0.1-0.0067=99.8143 (%)". On the other hand, the lower limit is 0.011% other than the total amount of oxygen contained in the raw material copper and the raw material copper, and the element contained in 0.01% of the impurity concentration in the alloy element is all other than the alloy element and oxygen. It is composed of the components, and is considered to be all that is calculated by subtracting the upper limit value. For example, in the case of the sample number 89, the lower limit value is "99.8143-0.998 × 0.011 - 0.001 × 0.1 - 0.001 × 0.1 = 99.8031 (%)".

The analytical value of the alloying element is, for example, shown by the result of sample number 89, although it is smaller than 0.1%, but it is mainly contained in the impurity or the oxygen or sulfur contained in the impurity. At the time of casting, it reacts with oxygen in the atmosphere to form an oxide or a sulfide, and is discharged to the upper portion or the surface layer portion of the ingot, and as a result, it is released as dirt at the time of pickling. Aluminum also confirms the degree of deoxidation effect, but in this case, the rare earth element may be the larger.

Next, the polyamic acid solution a prepared in the same manner as in Synthesis Example 1 of Example 1 was applied and dried (after hardening, a thermoplastic polyimide having a film thickness of 2 μm was formed), and coated thereon. The polylysine b prepared in the same manner as in Synthesis Example 2 of Example 1 was dried (after hardening, a low thermal expansion polyimine having a film thickness of 8 μm was formed), and polyamine was coated thereon. Acid a and dry it (hardened to form a thermoplastic polymer with a film thickness of 2 μm) The imine) is heated under the conditions of a maximum temperature of 360 ° C for 10 minutes at a cumulative time to form a polyimide layer (resin layer).

Then, it was cut into a length of 250 mm in the rolling direction (MD direction) along the copper foil, and the direction orthogonal to the rolling method (TD direction) was cut into a rectangular shape having a width of 40 mm to obtain a polymer having a thickness of 12 μm. A single-sided copper-clad laminate for testing of the ninth imide layer (resin layer) 1 and the copper foil layer 2 having a thickness of 12 μm according to Example 3 (Fig. 5). The tensile modulus of elasticity of the entire resin layer at this time was 7.5 GPa.

The structure analysis was carried out in the same manner as in Example 1 on the copper foil (copper foil layer) in the single-sided copper-clad laminate obtained above. In addition, a predetermined mask was coated on the side of the copper foil layer of the test single-sided copper-clad laminate, and etching was performed using a ferric chloride/copper chloride-based solution to form the same wiring pattern as in the first embodiment. Then, in the direction of the wiring direction H of the circuit board, it is 150 mm in the long-distance direction and orthogonal to the wiring direction H, in accordance with JIS 6471, which can also serve as a sample for the flexural test described later. A test flexible circuit board having a width of 40 mm. Here, the fact that the structure of the copper foil did not change before and after the formation by the circuit for etching was confirmed.

Then, a test flexible circuit board having the resin layer 1 and the wiring (copper foil) 2 was used as a test flexible circuit board as an IPC test sample in the same manner as in the second embodiment. Further, in the present embodiment, the polyimide layer (resin layer) 1 was formed outside, the gap length was made 1.5 mm, that is, the bending radius was made 0.75 mm, and the stroke was made to be 38 mm, and the rest was in accordance with the examples. 2 Implement the IPC test in the same way, and take the number of strokes of the circuit's resistance to twice the initial value as electricity. The road break life is obtained. In the same manner as in the second embodiment, the copper foil after the circuit breaking life is observed by using a scanning electron microscope to observe the cross section of the copper foil in the thickness direction so as to be orthogonal to the sliding direction. Although it was observed that there was a degree of difference, cracks occurred on the surface of each of the copper foils on the side of the resin layer and the side of the covering material, and in particular, a large number of cracks were introduced into the surface of the copper foil on the side of the resin layer on the outer side of the flexing portion.

The alloy component values, the <100> preferred orientation area ratio, and the flex life in the copper foil obtained by the above test are shown in Table 5 together with the sample number and the polyimide temperature. The (-) mark in the component value means the meaning of the unmeasured person. As shown in the sample No. 85, the oxygen concentration of the caster's copper foil melted in the Ar gas stream was lower than that of the raw material copper. This is due to melting at low oxygen concentrations. Deoxidation effect caused by casting. Further, samples of sample numbers 87, 91, 94, and 96 were melted under the same conditions by adding Ce, Y, Sm, and Ca. The founder knows that the area ratio of the <100> preferred orientation area is increased by the addition of these elements, and the result is an increase in the fatigue life measured by the IPC test. Further, when the results of the sample number 94 and the sample number 95 are compared, it can be known that when Al is added in addition to Sm, the fatigue life measured in the IPC test is increased.

On the other hand, as shown in the case of the sample number 86, the oxygen concentration of the copper foil is higher than that of the raw material copper when cast in the atmosphere. On the other hand, when the results of the sample numbers 88, 90, 92, and 96 are observed, the fact that the concentration of oxygen in the copper foil is lowered when Ce, La, Y, and Ca are added is known. This is why the elements have a deoxidizing effect. Among these samples, the reason for the increase in fatigue life measured by the IPC test may be due to rare earths. The class element enhances the direct effect of the area ratio of the <100> preferred orientation area and the melting factor. The deoxidation effect of the oxidation reaction at the time of casting. Further, it can be considered that the results of the sample numbers 89, 93, and 98 show the fact that aluminum reinforces the effect.

[Industrial use possibility]

The copper foil of the present invention is suitable as a flexible circuit substrate in various electrons. Widely used in electrical equipment, the user of the flexure is provided anywhere, in response to deformation of the circuit board itself, bending, or deformation of the loaded equipment. In particular, since the flexible circuit board of the present invention has a flexing portion structure excellent in flexural durability, it is suitable for repetition of sliding, flexing, flexing, bending, hinge bending, and the like. In the case where the movement is frequently bent, or in the case of miniaturization of the equipment to be loaded, a situation in which a flexing portion having a small radius of curvature is required is formed. Therefore, it can be suitably used for thin mobile phones, thin displays, hard disks, printers, DVD devices, and various electronic devices that require durability.

1‧‧‧ resin layer

2‧‧‧Wiring (metal foil)

3‧‧‧Connector terminals

6‧‧‧Adhesive layer

7‧‧‧ Covering materials

8‧‧‧ gap length

9‧‧‧Fixed Department

10‧‧‧ Guides Department

21‧‧‧ Normal direction of section P

L‧‧‧ ridgeline

P‧‧‧A section of the wiring when cut from the ridgeline of the flexure to the thickness direction

Fig. 1 is a plan view showing a relationship between a wiring formed by a copper foil layer of a flexible circuit board and a ridge line of a flexure portion.

Fig. 2 is a cross-sectional explanatory view showing a state in which a flexible circuit board is bent.

Fig. 3 is an explanatory view of the MIT flexure test apparatus.

Figure 4(a): Illustration of the IPC flexure test device, section 4(b) Fig.: X-X' sectional view of a flexible circuit board for testing using IPC flexural test.

Figure 5: A squint illustration of a single-sided copper laminate.

1‧‧‧ resin layer

2‧‧‧Wiring (metal foil)

3‧‧‧Connector terminals

L‧‧‧ ridgeline

Claims (19)

A copper foil containing Cu (copper) copper foil having Mn (manganese) of 0.001% by mass or more and 0.4% by mass or less and having unavoidable impurities and remainder, characterized in that the basic crystal axis of the unit crystal lattice of copper < 100> is a preferred orientation region in which the thickness direction of the copper foil and the two orthogonal axes existing in a certain direction of the foil surface are within 15 degrees of each azimuth difference, and the area ratio is 60% or more. . The copper foil according to the first aspect of the invention, which contains Mn in an amount of 0.001% by mass or more and 0.1% by mass or less, and contains 0.005% by mass or more and 0.2% by mass or less of Ti (titanium) or 0.005% by mass or more and 2% by mass or less of Al. At least one of (aluminum). A copper foil according to claim 1 or 2, which contains Mn 0.06 mass% or less. A copper foil containing a substance selected from the group consisting of Ca (calcium), La (镧), Ce (铈), Pr (鐠), Nd (钕), Sm (钐), Eu (铕), Gd (釓), Dy (镝), Ho(鈥), Er(铒), Tm(銩), Yb(镱), and Y(钇) are at least one element of 0.005 mass% or more and 0.4 mass% or less, and the remaining copper is 99.6. A copper foil having a mass % or more and 99.999 mass% or less is characterized in that the basic crystal axis of the unit crystal lattice of copper is <100>, which is formed by the thickness direction of the copper foil and a direction existing in the foil surface. The orthogonal axis, the preferred orientation area within 15° of each azimuth difference, accounts for more than 60% of the area ratio. A copper foil according to item 4 of the patent application, which contains 0.005 mass% or more and 0.2 mass% or less of Ti, or 0.005 mass% or more and 0.395. At least one of the mass % or less of Al. The copper foil of claim 1 or 2, wherein the oxygen content is less than 0.1% by mass. A copper-clad laminate having a copper foil layer formed of a copper foil according to any one of claims 1 to 6 and a resin layer laminated thereon. The copper-clad laminate according to claim 7, wherein the thickness of the copper foil layer is 5 μm or more and 18 μm or less, and the thickness of the resin layer is 5 μm or more and 75 μm or less. A copper clad laminate according to claim 7 or 8, wherein the resin layer is made of polyimine. A flexible circuit board characterized in that a copper foil layer of a copper-clad laminate according to any one of claims 7 to 9 is etched to form a specific wiring, and the wiring is Use at least one part to form the flexure. The flexible circuit substrate of claim 10, wherein the repetitive motion of the group is selected from the group consisting of sliding flexing, bending flexing, hinge flexing, and bending of the guide plate. The user of the way of the scratch. An electronic device characterized in that the flexible circuit board described in claim 10 or 11 is loaded. A method for producing a copper-clad laminate, which is a method for producing a copper-clad laminate having a copper foil layer and a resin layer, characterized in that it contains Mn in an amount of 0.001% by mass or more and 0.1% by mass or less, and is inevitably formed in composition. The surface of the cold-rolled copper foil of the impure material and the remaining part of Cu is coated with a polyaminic acid solution and subjected to heat treatment, or the polyimide film is overlapped and then subjected to thermocompression bonding, thereby forming a poly-pyrene on the cold-rolled copper foil. The resin layer formed by the amine simultaneously recrystallizes the cold-rolled copper foil, and the basic crystal axis of the unit crystal lattice of copper is <100>, and the thickness direction of the copper foil and the direction existing in the foil surface can be The two orthogonal axes formed, the preferred orientation regions within 15° of each azimuth difference, occupy 60% or more of the copper foil layer in terms of area ratio. The method for producing a copper-clad laminate according to claim 13, wherein the cold-rolled copper foil further contains 0.005 mass% or more and 0.2 mass% or less of Ti, or at least 0.005 mass% or more and 2 mass% or less of at least one of Al. . The method for producing a copper-clad laminate according to the 13th or 14th aspect of the invention, wherein the cold-rolled copper foil contains 0.06 mass% or less of Mn. A method for producing a copper-clad laminate, which comprises a copper foil layer and a resin layer, wherein the pair contains Ca, La, Ce, Pr At least one element of Dy, Ho, Er, Tm, Yb, and Y is 0.005 mass% or more and 0.4 mass% or less, and the remaining copper is 99.9% by mass or more and 99.999 mass% or less of the surface of the cold-rolled copper foil. The polyaminic acid solution is subjected to heat treatment, or the polyimide film is laminated and then subjected to thermocompression bonding, whereby a resin layer made of polyimine is formed on the cold-rolled copper foil, and the cold-rolled copper foil is recrystallized. The basic crystal axis of the unit crystal lattice of copper is <100>, and the thickness direction of the copper foil and the two orthogonal axes formed in a certain direction in the foil surface can be within 15° of each orientation difference. The preferred orientation area, in terms of area ratio, Occupy more than 60% of the copper foil layer. The method for producing a copper-clad laminate according to claim 16, wherein the cold-rolled copper foil contains at least one of 0.005 mass% or more and 0.2 mass% or less of Ti or 0.005 mass% or more and 0.395 mass% or less of Al. The method for producing a copper-clad laminate according to claim 13 or 16, wherein the applied polyamine solution is subjected to heat treatment to form a resin layer having a temperature of from 280 ° C to 400 ° C. The method for producing a copper-clad laminate according to claim 13 or 16, wherein the polyimide film is subjected to thermocompression bonding to form a resin layer at a temperature of from 280 ° C to 400 ° C.