KR101721314B1 - Rolled copper foil, copper clad laminate, and flexible printed board and electronic device - Google Patents

Abstract

[PROBLEMS] To provide a rolled copper foil, a copper clad laminate, a flexible printed circuit board, and an electronic apparatus excellent in both etching property and flexibility.
(Solution) A rolled copper foil containing 99.9% by mass or more of copper in terms of a mass ratio is subjected to a heat treatment under either of the conditions of 350 占 폚 for 1 second, 350 占 폚 for 20 minutes, or 200 占 폚 for 30 minutes, 102} is not less than 1% and not more than 50%.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a rolled copper foil, a copper clad laminate, a flexible printed circuit board,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rolled copper foil, a copper clad laminate, and a flexible printed circuit board and an electronic apparatus which are preferably used for an FPC (Flexible Printed Circuit Board) or the like.

BACKGROUND ART An FPC (Flexible Printed Circuit) is used as a method of performing wiring for a moving part of an electronic device or a part having a space limitation. As the FPC, a copper clad laminate formed by laminating a copper foil and a resin layer is used.

The FPC is bent and used in the apparatus, and the bending radius of the FPC is reduced along with the miniaturization of the apparatus, and the bending property of the FPC is required to be improved. Further, thereafter, wearable terminals are expected to be widespread, and the FPC is also required to be improved in fatigue characteristics. Further, with the miniaturization of the wiring of the FPC, the etching property of the copper foil in forming a circuit is also required.

However, it is general that the FPC is used while the copper foil is recrystallized. When the copper foil is rolled, the crystal is rotated to form a rolled aggregate structure. Then, the rolled copper foil is annealed after rolling, or recrystallized when heat is applied in the process until the final product is processed, in other words, until the FPC is obtained. The recrystallized structure after being rolled copper foil is referred to simply as " recrystallized structure " hereinafter, and the rolled structure before heat is applied is simply referred to as " rolled structure ". The recrystallized structure largely depends on the rolled structure, and the recrystallized structure can be controlled by controlling the rolled structure.

In view of this, a technique has been proposed in which the (200) plane ({100}) which is the Cube orientation is developed as the recrystallized structure of the rolled copper foil to thereby improve the bendability (for example, Patent Document 1).

Japanese Unexamined Patent Application Publication No. 11-286760

However, when the orientation of the Cube of the copper foil is excessively developed, there is a problem that the etching property is deteriorated. This is considered to be due to the fact that even if the Cube set texture is developed, it is in a mixed state in which small crystal grains of different orientations are present in large crystal grains of the Cube orientation rather than a single crystal, and the etching rate varies in each orientation grain. Particularly, as the L / S width of the circuit is narrowed (fine pitch), the etching property becomes a problem. In addition, if the orientation of the Cube is excessively developed, the copper foil becomes excessively flexible, and the handling property may deteriorate.

Therefore, there is a demand for a technique for improving the flexural properties without developing the Cube bearing. Also, the Cube bearing is the recrystallization set bearing of the pure copper system.

Accordingly, an object of the present invention is to provide a rolled copper foil, a copper clad laminate, and a flexible printed circuit board and an electronic apparatus which are excellent in both etching and bending properties.

The present inventors paid attention to the rolled copper foil {102} as a method for improving the flexural properties without developing the Cube orientation. When {102} is developed on the surface of the plate, the flexibility and bending property can be improved while ensuring the same etching property as that of the conventional electrolytic copper foil in which the Cube orientation is not developed. The reason why {102} improves the flexural and bending properties is considered to be that the Young's modulus is not as high as the Cube orientation but low. In addition, {100} means a (100) plane or a (100) plane.

That is, the rolled copper foil of the present invention contains copper in a mass ratio of 99.9% or more and is subjected to heat treatment under any one of conditions of 350 ° C x 1 second, 350 ° C x 20 minutes, or 200 ° C x 30 minutes, The ratio of crystal grains in the angular difference within 10 degrees from {102} is 1% or more and 50% or less.

The rolled copper foil of the present invention is a rolled copper foil containing 10 to 300 mass ppm in total of one or more selected from the group consisting of Ag, Sn, Zn, Ni, Ti, and Zr in total and containing the remainder Cu and inevitable impurities desirable.

The copper clad laminate according to the present invention is characterized in that the rolled copper foil is laminated on both sides or one side of the resin layer and the ratio of the crystal grains in the angular difference of 10 degrees or less from the surface {102} Is not less than 1% and not more than 50%.

The flexible printed board of the present invention is formed by forming a circuit in the rolled copper foil using the copper clad laminate.

The electronic apparatus of the present invention is formed using the flexible printed circuit board.

According to the present invention, it is possible to obtain a rolled copper foil excellent in both etching property and flexibility.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a view showing a test method of 180 ° contact bending.
2 is a view showing a bending test method.

Hereinafter, a rolled copper foil according to an embodiment of the present invention will be described. In the present invention, "% " means mass% unless otherwise specified. The rolled copper foil according to the embodiment of the present invention is useful for use as an FPC by removing other parts than the circuit part by post-etching with a resin laminated with a copper clad laminate.

<Composition>

The rolled copper foil contains at least 99.9% by mass of copper. Examples of such a composition include tough pitch copper specified by JIS-H3510 (C1011) or JIS-H3100 (C1020), JIS-H3100 (C1100), or taff pitch copper specified by JIS-H3100 (C1201 and C1220) Shandong can be heard. The upper limit of the oxygen content in the copper is not particularly limited, but is generally 500 mass ppm or less, more usually 320 mass ppm or less.

And may contain one or more elements selected from the group consisting of Ag, Sn, Zn, Ni, Ti, and Zr in a total amount of 10 to 300 mass ppm. In order to develop {102}, it is necessary to develop {112} by intermediate annealing of the rolled copper foil (annealing before final cold rolling). When these elements are added, the range of conditions for developing {112} The {102} can be more reliably developed, and manufacturing is facilitated. When the total amount of the above elements is less than 10 mass ppm, the effect of developing {112} by the intermediate annealing is small. When the mass exceeds 300 mass ppm, the conductivity is lowered and the recrystallization temperature is raised. It may be difficult to recrystallize while suppressing surface oxidation.

<Thickness>

The thickness of the copper foil is preferably 4 to 100 占 퐉, more preferably 5 to 70 占 퐉. If the thickness is less than 4 mu m, the handling property of the copper foil may be lowered. If the thickness exceeds 100 mu m, the foaming property of the copper foil may be deteriorated.

&Lt; 102 >

The surface of the rolled copper foil has a ratio of crystal grains having an angle difference of 10 degrees or less from the surface of the rolled copper foil after being subjected to the heat treatment under any one of the conditions of 350 DEG C x 1 second, 350 DEG C x 20 minutes, or 200 DEG C x 30 minutes 1% or more and 50% or less. The &quot; surface &quot; of the rolled copper foil refers to the surface after polishing the outermost surface by electrolytic polishing at 0.5 to 2 占 퐉.

Here, the etching (particularly soft etching) is affected by the plane orientation of the crystal grains on the surface of the copper foil. Also, the bending property and the bending property are caused by the greatest deformation applied to the surface of the copper foil. In this respect, the degree of development of {102} of the copper foil surface (rolled surface) is defined. However, when the oxide layer, the rust prevention layer, and the like are present on the surface of the copper foil and it is necessary to remove them, the surface after removal is regarded as the copper foil surface. Generally, if the surface of the copper foil is removed to a thickness of 1 mu m or less, the plane orientation can be measured, and it is considered that there is no difference in the orientation before and after the removal.

Since the crystal grains in the angular difference within 10 degrees from {102} can be regarded as the surface in the vicinity of {102}, they are defined in this manner. If the angle difference from {102} exceeds 10 degrees, the difference from {102} becomes larger.

The rolled copper foil is usually shipped in the state of &quot; rolled structure &quot;, and when the copper clad laminate is manufactured, it is recrystallized when it is combined with the resin layer to form a recrystallized aggregate structure. Therefore, in order to evaluate the bendability, bending property, and etching property of the copper clad laminate, it is necessary to target the "recrystallized structure" of the rolled copper foil. On the other hand, the recrystallized structure is not determined only by the rolling structure but varies greatly depending on the temperature condition at the time of recrystallization.

Therefore, in the typical production method of the copper clad laminate, the thermal history of the rolled copper foil is reproduced simulatively at 350 ° C. × 1 second, 350 ° C. × 20 minutes, or 200 ° C. × 30 minutes to obtain a recrystallized It is assumed that the state of the copper foil is indicated.

Therefore, the heat treatment itself is carried out in any one of the three conditions. After the heat treatment at 350 占 폚 for 1 second, the second sample is not subjected to the heat treatment at 350 占 폚 for 20 minutes. However, for example, the ratio of the crystal grains may be 1% or more and 50% or less both when the heat treatment is performed at 350 占 폚 for 1 second and when the heat treatment is performed at 350 占 폚 for 20 minutes.

And, when the ratio of the crystal grains in the angular difference of 10 degrees or less from the plane orientation of the copper foil surface is {102} is 1% or more, {102} is developed and the bending property and the folding property of the copper clad laminate are improved. On the other hand, it is industrially difficult to increase the ratio of the crystal grains to more than 50%.

The plane orientation of the copper foil surface is measured by EBSD (electron backscatter diffraction). The EBSD can measure the crystal orientation in the vicinity of the sample surface by the resolution of the order of nm, and can calculate the local crystal orientation change (local orientation difference) from the measurement data. From these data, the ratio of crystal grains in the angular difference within 10 degrees from {102} is calculated.

In addition, the EBSD has a wider measurement area, which results in wider measurement intervals, which is undesirable. On the other hand, when {100} is developed on the rolled surface, the crystal grain size increases up to about 100 μm. In this case, however, the measurement area is set to 4 mm 2 so that a sufficient number of crystal grains are present in the measurement region. The interval between the measurement points is set to 1 占 퐉 or less. In this case, since it is difficult to measure the entire area of 4 mm 2 by one measurement, a randomly extracted place is measured a plurality of times, and the sum of the measurement areas becomes 4 mm 2.

The rolled copper foil of the present invention is usually subjected to hot rolling and surface cutting after cold rolling and annealing several times (usually about twice), followed by final recrystallization annealing, final cold rolling, can do. After the copper foil is degreased, the copper foil is subjected to a roughening treatment on one side (a lamination surface with the resin layer) to ensure adhesion with the resin layer, and the copper foil can be used again for the copper clad laminate.

The term &quot; final recrystallization annealing &quot; refers to the last annealing before final cold rolling.

In order to develop {102} of the copper foil surface as described above, the integral diffraction intensity ratio I (200) of X-ray diffraction indicating the degree of development of the crystal having {100} before the final cold rolling after "final recrystallization annealing" ) / I ₀ (200)) is in the range of 2 to 10. The intensity (I / I ₀ ) of the (200) plane obtained by X-ray diffraction of the intensity (I (200)) of the integral diffraction intensity obtained by X-ray diffraction of the rolled surface and the fine powder copper And the diffraction intensity (I ₀ (200)), indicating the degree of development of the cube (cube assembly) structure.

If {I (200) / I ₀ (200)) is less than 2, {200} is gathered in the finally obtained copper foil after the final cold rolling, so that {102} of the copper foil surface is not developed. This is because when (I / I ₀ ) is small in the final recrystallization annealing step, then the ratio I (200) / I ₀ (200) increases at the time of the final cold rolling, } Is not developed.

On the other hand, if the above (I (200) / I ₀ (200)) exceeds 10, the surface of the copper foil becomes randomly close to the orientation, and {102} is not developed. This is because, when I (200) / I ₀ (200) before final cold rolling exceeds 10, there is a random orientation near to the final cold rolling, and {102} is not developed.

The final recrystallization annealing after the final cold rolling (I (200) / I ₀ (200)) is controlled to 2 to 10 by performing the final recrystallization annealing at a temperature of 600 ° C or higher, And the passage time of ~ 500 ° C may be controlled to 5 to 60 seconds. If the passage time is less than 5 seconds, I (200) / I ₀ (200) becomes less than 2, and if it exceeds 60 seconds, I (200) / I ₀ (200) exceeds 10. In addition, the cooling process after the temperature is once raised and subjected to the &quot; final recrystallization annealing &quot; does not affect the generation of {102}.

In order to develop the {102} orientation of the surface of the copper foil, the final degree of cold rolling (eta) is controlled to be 2.8 to 3.7. When? is less than 2.8, the surface of the copper foil is randomly oriented and {102} is not developed. When? is more than 3.7, {100} is gathered and {102} of the surface of the copper foil does not develop.

In addition, η = ln (A / B), and A and B are sectional areas before cold rolling and after final cold rolling, respectively.

The copper clad laminate of the present invention is formed by laminating rolled copper foils having the above properties on both sides or one side of a resin layer. The resin layer is not particularly limited as long as it has characteristics applicable to a printed wiring board and the like. For example, for the rigid PWB, a paper base phenol resin, a paper base epoxy resin, a synthetic fiber base epoxy resin, a glass cloth, Epoxy resin, glass / glass nonwoven fabric composite base epoxy resin, and glass cloth base epoxy resin. A polyester film, a polyimide film, a liquid crystal polymer (LCP) film, a Teflon (registered trademark) film, a polyethylene terephthalate film, a polyethylene naphthalate film, or the like can be used for the FPC.

The resin layer itself may be multilayered.

Further, when the copper foil is brought into contact with the resin layer having low heat resistance such as polyethylene terephthalate, there is a possibility that the copper foil in the state of "rolled tissue" may not become the above-mentioned "recrystallized structure" depending on the thermocompression conditions at the time of sticking. In this case, any one of the above-mentioned 350 ° C x 1 second, 350 ° C x 20 minutes, or 200 ° C x 30 minutes heat treatment is performed on the copper foil to recrystallize the crystal grains, May be adjusted to 10% or more, and then the laminate may be bonded to the resin layer to form a copper clad laminate.

Depending on the configuration of the FPC, only one of the copper foils of the copper clad laminate may be severely bent or bent. When the copper foil is used for such a purpose, the copper foil is laminated on both sides of the resin layer of the copper clad laminate, the copper foil of the present invention is used on one copper foil side where severe bending conditions are applied, For example, an inexpensive electrolytic copper foil may be laminated.

The method for laminating a rolled copper foil and a resin includes the steps of preparing a prepreg in which a base material such as a glass foil is impregnated with a resin and the resin is hardened to a semi-hardened state, and the copper foil is superposed on the prepreg and heated and pressed Method. In the case of FPC, a copper clad laminate can be produced by adhering a copper foil to a resin layer such as a polyimide film through an adhesive or by laminating copper foils under high temperature and high pressure without using an adhesive. In the case of FPC, a copper clad laminate can be produced by applying a polyimide precursor to a rolled copper foil, followed by drying and curing.

The thickness of the resin (layer) is not particularly limited, but it is generally about 9 to 50 mu m. In addition, a thick resin having a thickness of 50 탆 or more may be used. The upper limit of the thickness of the resin is not particularly limited, but is, for example, 150 占 퐉.

The copper clad laminate of the present invention can be used for various flexible printed boards (printed wiring board (PWB)). The printed wiring board is not particularly limited, but is applicable to single-sided PWB, double-sided PWB, multilayer PWB (three or more layers) from the viewpoint of the number of layers of the conductor pattern, for example. The present invention is applicable to Rigid PWB, Flexible PWB (FPC) and Rigid Flex PWB from the viewpoint of kinds of insulating substrate materials.

Example

<Production of rolled copper foil>

An ingot having a thickness of 100 mm was cast using tough pitch copper or oxygen-free copper added with an element of the composition shown in Table 1 as a raw material, and hot rolling was performed at 800 캜 or higher to a thickness of 10 탆 to finish the oxide scale of the surface . Thereafter, cold rolling and annealing were repeated to obtain a rolled sheet coil having a thickness of 0.5 mm. After the subsequent cold rolling, final recrystallization annealing was carried out under the conditions shown in Table 1. Finally, a predetermined thickness (Examples 9, 6 and 13 have a thickness of 9 占 퐉, Example 7 has a thickness of 18 占 퐉, and the other Examples and Comparative Examples 1 to 4 have a thickness of 12 占 퐉) Respectively.

&Quot; OFC + 30 ppm Ag &quot; in the composition column in Table 1 means that 30 mass ppm of Ag was added to the oxygen-free copper OFC of JIS-H3100 (C1020). "TPC + 200 ppm Ag" means that 200 mass ppm of Ag is added to tough pitch copper (TPC) of JIS-H3100 (C1100). The same is true for other addition amounts.

<Integrated diffraction intensity ratio of X-ray (I (200) / I ₀ (200))>

The X-ray diffraction intensity of the {100} plane was measured on the surface of the copper foil after the final recrystallization annealing and before the final cold rolling. Then, the value of the pure powder (I ₀ (200): X-ray reflection average intensity) subjected to X-ray diffraction under the same conditions was standardized.

X-ray diffraction measurement conditions were as follows: incident X-ray source: Cu, acceleration voltage: 25 kV, tube current: 20 mA, divergent slit: 1 degree, scattering slit: 1 degree, light receiving slit: 0.3 mm, Mm, and a monochrome light receiving slit: 0.8 mm. Fine powders (325 mesh) were used as the pure powders.

&Lt; Crystal orientation >

The copper foil after the final cold rolling was further subjected to the respective heat treatments shown in Table 1, and the surface was lightly electrolytically polished to perform EBSD measurement of the surface. The measurement area was 4 mm &lt; 2 &gt; in total as described above. Using the analysis software attached to the EBSD apparatus (OIM Analysis by TSL Solutions), the ratio of crystal grains in the angular difference within 10 degrees from the plane orientation of {102} of the surface was calculated.

Also, in the heat treatment at 350 占 폚 for 1 sec, even if the copper foil is simply put in the furnace at 350 占 폚 for 1 second, the time is short and the heat treatment at 350 占 폚 占 1 sec is not performed. Thus, a copper foil was sandwiched between two stainless steel plates (SUS410 / thickness 5 mm, Ra 0.1, and Rz 0.6) at 350 占 폚 for one second to perform a heat treatment at 350 占 폚 for 1 sec.

The heat treatment at 350 ° C for 20 minutes and at 200 ° C for 30 minutes, respectively, was conducted by charging copper foil in a furnace at 350 ° C and 200 ° C for a predetermined time, respectively.

&Lt; Preparation of copper clad laminate &

A rolled copper foil of each of Examples and Comparative Examples in Table 1 was laminated with a resin layer by a lamination method shown in Table 2 to prepare a copper clad laminate. For the rolled copper foil of Table 1, those before the heat treatment of Table 1 were used.

The thickness of the resin layer was 50 탆 for Example 3, 35 탆 for Examples 8, 12 and 19, and 25 탆 for other Examples and Comparative Examples 1 to 4. Among the resin layers, the polyimide and epoxy were thermosetting, and the liquid crystal polymer was thermoplastic. The term &quot; polyimide / epoxy &quot; refers to a multilayer resin layer in which a polyimide layer and an epoxy layer are laminated, and the epoxy layer side is bonded to the copper foil as an adhesive layer, as shown in a lamination method &quot; C &quot;

In Table 2, when the lamination of the copper foil is &quot; both surfaces &quot;, the copper foil is laminated on both surfaces of the resin layer.

In Table 2, the lamination method "A" is a method in which a laminate obtained by laminating a commercially available thermoplastic-added polyimide film or a liquid crystal polymer film and a copper foil is set between two stainless steel plates (SUS410) And held for 1 second. The thermoplastic-added polyimide film refers to a polyimide film in which a polyimide film having a thermoplasticity of 2 占 퐉 is adhered to the substrate surface of a polyimide film in advance, since a conventional polyimide film is thermosetting and therefore does not adhere to heat .

In the lamination method "B", a commercially available polyimide precursor varnish was applied to a copper foil, followed by drying and curing. The drying temperature was 200 占 폚 for 3 minutes and the cure was 350 占 폚 for 30 minutes.

The lamination method "C" is a method in which a commercially available polyimide film is coated with a commercially available epoxy adhesive, followed by drying to evaporate the solvent in the epoxy adhesive, coagulate the copper foil again, and cure (cure) the adhesive. The drying temperature was 200 占 폚 for 3 minutes and the cure was 200 占 폚 for 30 minutes.

The obtained copper clad laminate was subjected to the following evaluation.

&Lt; Crystal orientation >

As in the case of the rolled copper foil, the ratio of crystal grains in the angular difference within 10 degrees from the plane orientation of {102} to the copper foil surface of the copper clad laminate was measured. When the copper foil is laminated on both surfaces of the copper clad laminate, the copper foil surface is optionally measured on one of the copper foil surfaces.

However,

The following bending property and bending property were evaluated in terms of bending property with a small number of cycles until the specimen was cracked and bending property with a large number of cycles.

The copper clad laminate was repeatedly subjected to 180 ° close bending, and the number of times until the copper foil was cracked was measured. The presence or absence of cracking was observed with a CCD camera after the bending of the copper foil surface (curved outer surface). It was rated as ○ when it bend 3 times and not divided as 3 times.

The 180 ° contact bending is carried out as shown in Fig. First, the test piece is cut into a short plate of 12.7 mm x 100 mm such that the rolling direction of the copper foil is the longitudinal direction. The test piece (S1) was bent in a U-shape at the center so as to meet both ends in the longitudinal direction, and the test specimen (S1) was placed in a reverse tester C- (Fig. 1 (a)). Specifically, the test piece S1 is placed on the pedestal 12 of the compression tester and the crosshead 11 above the test piece S1 is subjected to a load of 98 kN (10 kgf) and 50 mm / min , And the test piece (S1) is completely crushed by holding it for 5 seconds after the load is applied. Thereafter, the crosshead 11 is raised to take out the test piece S2 which is crushed by the U-shaped portion, and the direction of the test piece S2 is changed so that the lengthwise direction is up and down, thereby obtaining a test piece S3 (FIG. The test pieces S2 and S3 have bent portions C in which the U-shaped portions are crushed and protruded.

The test piece S3 is placed on the pedestal 12 of the compression tester so that the bending portion C is upward and the crosshead 11 above the bending portion C is placed at the same load and speed And the test piece S3 is completely crushed by maintaining the load for 5 seconds after the load is applied (Fig. 1 (c), (d)). Thereafter, the crosshead 11 is raised to take out the test piece S4 whose bending portion C is crushed and becomes almost flat, and the bent outer surface Sk of the predetermined region around the bending portion C is observed , And judges the presence or absence of cracking (Fig. 1 (e)).

<Flexibility>

After the copper foil of the copper clad laminate was etched to form a predetermined circuit, a bending test was conducted by an IPC (American Printed Circuit Industry) bending test apparatus shown in Fig. The electrical resistance of the circuit portion was measured during the sliding bending test to determine that the resistance value did not break when the resistance value was increased by 15% from the beginning and that the number of bending times exceeded 10000, And the sample which was broken at the time point was rated as x.

This IPC bending test apparatus has a structure in which the vibration transmitting member 3 is coupled to the oscillation drive body 4 and the test piece 1 has a total of four points of the screw 2 portion indicated by the arrow and the tip portion of the Lt; / RTI &gt; When the vibration portion 3 is driven up and down, the intermediate portion of the test piece 1 is bent on the hair pin at a predetermined radius of curvature r.

The test conditions were as follows: specimen width: 12.7 mm; specimen length: 200 mm; specimen collection direction: taken such that the longitudinal direction of the specimen was parallel to the rolling direction; radius of curvature (r): 1.5 mm; 25 mm, vibration speed: 1500 times / minute

When the copper foil is formed on one side of the copper clad laminate, the copper foil is directed to the curved inner surface of the radius of curvature r in Fig. When the copper foil is laminated on both surfaces of the copper clad laminate, the copper foil surface on which the crystal orientation is measured is etched to form a circuit, and the copper foil on the opposite surface is completely removed by etching. This circuit surface was defined as a curved inner surface having a curvature radius r shown in Fig.

The etchability was determined by the following circuit linearity and half-etchability. When the copper foil was laminated on both surfaces of the copper clad laminate, the copper foil surface on which the crystal orientation was measured was etched.

The circuit linearity is obtained by masking a circuit pattern on a copper foil of a copper clad laminate with a width of 50 占 퐉 and a lengthwise direction on the surface of the copper foil and spraying 50 占 폚 of ferric chloride on the copper foil surface by spray etching Thereby forming a short circuit circuit having a width of 탆. The circuit width in the width direction was measured by SEM at a pitch of 5 占 퐉 in the longitudinal direction of the circuit. When 100 points were measured at the above-mentioned pitch, the case where the 3σ of the normal distribution of the circuit width was within 2 占 퐉 was evaluated as?.

The half etching was performed by etching the copper foil with a mixed aqueous solution of sodium persulfate (40 g / l) and sulfuric acid (20 g / l) until the thickness of the copper foil reached the initial half and cutting the cross section with CP (cross section polisher) Then, the thickness of each cross section was measured by SEM at a pitch of 5 탆 along the etched plane orientation. When 100 points were measured at the above pitches, the case where the 3σ of the normal distribution of thickness was within 2 占 퐉 was evaluated as?.

In the evaluation of the etching property, a case in which the circuit linearity and the half-etching property were all? Was evaluated as the overall evaluation?, And a case in which neither the circuit linearity nor the half etching was?

The obtained results are shown in Tables 1 and 2.

As apparent from Tables 1 to 2, in the case of each embodiment in which the ratio of the crystal grains in the angular difference within 10 degrees from the plane orientation of the copper foil surface in the copper clad laminate was 1% or more and 50% or less, Curvature, bendability and etchability were both excellent.

When the copper foil before lamination to the copper clad laminate of each example is subjected to heat treatment at 350 ° C for 1 second, 350 ° C for 20 minutes, or 200 ° C for 30 minutes, the surface orientation of the surface is within 10 degrees from {102} Of the crystal grains in the angle difference was 1% or more and 50% or less.

On the other hand, compare the in the temperature rising stage at the time of the final recrystallization annealing of the copper foil is passed through time of 200 ~ 500 ℃ more than 60 seconds in Example 1, for 2, (I (200) / I 0 (200)) the copper foil beyond this 10 The surface became randomly oriented, and {102} was not developed, and the ratio of crystal grains in the angle difference within 10 degrees from the plane orientation of the copper foil surface from {102} became less than 1%. Therefore, in the case of Comparative Examples 1 and 2, bending property and bending property were inferior.

In the case of Comparative Examples 3 and 4 in which the final cold rolling of the copper foil had a processing degree (?) Of more than 3.7, the X-ray diffraction intensity ratio (I (200) / I ₀ (200)) after the final recrystallization annealing was less than 2 Therefore, the ratio of crystal grains having an angle difference of less than 10 degrees from the plane orientation of the copper foil surface of {102} is 1 % &Lt; / RTI &gt; Therefore, in the case of Comparative Examples 3 and 4, the bending property and the bending property were improved, but the etching property was inferior.

Claims (5)

A rolled copper foil containing 99.9% by mass or more of copper as a mass ratio,
After a heat treatment is performed under any one of conditions of 350 占 폚 for 1 second, 350 占 폚 for 20 minutes, or 200 占 폚 for 30 minutes, the ratio of crystal grains having an angle difference of 10 degrees or less from the surface {102} Rolled copper foil of 50% or less. The method according to claim 1,
Ag, Sn, Zn, Ni, Ti, and Zr in a total amount of 10 to 300 mass ppm, and the balance Cu and inevitable impurities. A copper clad laminate obtained by laminating the rolled copper foil according to claim 1 or 2 on both sides or one side of a resin layer,
Wherein the ratio of the crystal grains in the angular difference of 10 degrees or less from the surface {102} in the at least one rolled copper foil is 1% or more and 50% or less. A flexible printed circuit board comprising a copper clad laminate according to claim 3 and a circuit formed on the rolled copper foil. An electronic device using the flexible printed circuit board according to claim 4.

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