JP4522972B2 - High gloss rolled copper foil for copper-clad laminates - Google Patents

Description

  The present invention relates to a rolled copper foil having excellent bending resistance suitable for use as a flexible wiring member such as a flexible printed circuit (FPC).

Printed circuit boards based on organic materials are rigid copper clad laminates (rigids) composed of glass epoxy and paper phenolic substrates, and flexible copper clad laminates (FPC) composed of polyimide and polyester substrates. FPC when using copper foil as the conductive material is divided into a casting method and a laminate method. In the casting method, a copper foil is coated with a resin and heated. In the lamination method, the copper foil is bonded to the resin with an adhesive. In recent years, a multilayer wiring board called a build-up board is often used as an effective means for high-density mounting. A rolled copper foil is mainly used as a copper foil that is a constituent member of the FPC.
Flexible printed circuit boards (FPC) are widely used in places where wiring to moving parts such as the head part of a printer or a head carriage part in a hard disk drive device is required, and bend over 1 million times according to the operation of the moving part. Is repeated. For this reason, rolled copper foil, which is the material of FPC, is required to have high bending resistance.In recent years, with the downsizing of equipment and the advancement of functions, the usage environment of FPC has become more intense than before, and rolled copper foil Is required to have a higher level of bending resistance than ever before.
The FPC bend is a bend with a large curvature, that is, a bend in a low strain state (hereinafter referred to as a low strain bend load). However, the number of repetitions is as many as tens of thousands or hundreds of thousands. It is.

  For example, tough pitch copper (oxygen content of 100 to 500 mass ppm) or oxygen-free copper (oxygen content of 10 mass ppm or less) is used as the material of the rolled copper foil used for FPC, and after hot rolling these ingots Then, cold rolling and annealing are repeated to a predetermined thickness, and finally, the final cold rolling is used to finish the thickness to 50 μm or less to produce a rolled copper foil. Thereafter, the surface of the rolled copper foil is roughened to improve the adhesion to the resin substrate. The rolled copper foil after the rough plating is cut and then bonded to the resin substrate. For bonding the rolled copper foil and the resin, for example, an adhesive made of a thermosetting resin such as epoxy is used, and after the lamination, it is heated and cured at a temperature of 130 to 170 ° C. for several hours to several tens of hours. Next, the rolled copper foil is etched to form various wiring patterns.

Fatigue properties of rolled copper foil for FPC under repeated conditions of low strain bending load are significantly higher than those in the final cold rolled state by heating under conditions that cause recrystallization after the final cold rolling. improves. The reason for this is presumed to be that when a cold rolled material of pure copper is heated under conditions that cause recrystallization, a cubic texture (200) develops, and as a result, the Young's modulus in the deformation direction decreases. Therefore, the rolled copper foil is used as a component of the FPC after being heated under conditions that cause recrystallization after the final cold rolling. This heat treatment is performed by roughening plating and cutting, or heat treatment or bonding to the resin substrate. It also serves as heating. In Patent Document 1, the integrated intensity (I) of the (200) plane of finely divided copper (I ₀ ) obtained by X-ray diffraction of the rolled surface after heating under conditions that cause recrystallization. A rolled copper foil having a cubic texture with a ratio I / I ₀ > 20 is disclosed and manufactured by controlling the final cold rolling and annealing steps.

In addition to the above, the surface condition of the foil may be mentioned as a factor that affects the bending resistance of the rolled copper foil. When the copper material is cold-rolled, the unevenness on the surface of the rolled material has a certain thickness between the roll and the material by transferring the unevenness of the rolling roll surface to the surface of the rolled material (transfer of the roll surface). There are oil pits (fine irregularities) generated by the rolling oil film present at The size, form and distribution of the oil pits can be controlled by adjusting rolling conditions such as the rolling roll diameter, rolling roll surface roughness, rolling degree, rolling speed, and rolling oil viscosity. The pit caused by the oil pit has an acute angle at the tip of the pit, so repeated bending deformation of the rolled copper foil causes the crack to become a starting point of cracking due to stress concentration, thus reducing the bending fatigue life. Cause. Deeper oil pits tend to be the starting point of fatigue failure. Therefore, in Patent Document 2, on the surface formed by cold rolling, the oil pit depth h (corresponding to the maximum height Ry in accordance with JIS B0601-1994) is 2.0 μm or less to improve the bending resistance. I am trying.
Japanese Patent No. 3009383 JP 2001-58203 A

However, there is a limit to the improvement of the bending resistance by the development of the recrystallized cube texture that defines the rolling degree of the final cold rolling and the crystal grain size before the final cold rolling as in Patent Document 1 described above. For example, although the softening temperature of the rolled copper foil and cubic texture adjusts the manufacturing process of the rolled copper foil so as to more developed is reduced, has a proven track record are conventionally used, which has been determined in the manufacturing conditions, the It is actually difficult to change its softening properties. Furthermore, a rolled copper foil having a remarkably low softening temperature is softened during storage at room temperature, and wrinkles are likely to occur, making handling difficult.
In Patent Document 2, the depth of the oil pit is defined to improve the bending resistance, but when the oil pit depth is shallow, the maximum height Ry is 2.0 μm. Some have poor flexibility due to dense oil pits. That is, the unevenness of the density of the minute irregularities including the oil pits on the rolling surface contributes to the decrease in the bending fatigue life and the variation in the life in the same lot, and the maximum height Ry in Patent Document 2 is 2. The specification of 0.0 μm is insufficient.

In the past, the thickness of the rolled copper foil for FPC was mainly 35 μm, and the bending fatigue life (number of times) was usually required to be 30,000 times. In recent years, however, the amount of 18 μm rolled copper foil, which is half the thickness of the conventional one, has been increasing and is now becoming mainstream. The thickness of the rolled copper foil and the bending fatigue life (number of times) required by the thickness have an inverse logarithmic relationship. Therefore, the bending fatigue life (number of times) of the 18 μm rolled copper foil is about 300,000 times or more. Improvement is desired.
Then, this invention aims at providing the rolled copper foil which can improve the bending resistance of the conventional rolled copper foil, without reducing other characteristics, and can be used on the conditions which a low distortion bending load repeats. .

The present invention relates to the rolled copper foil described below.
(1) After heating for 30 minutes at 200 ° C., the ratio I of the integrated intensity (I) of the (200) plane obtained by X-ray diffraction of the rolled surface to the integrated intensity (I ₀ ) of the (200) plane of finely powdered copper In the rolled copper foil having / I ₀ of 20 or more, Gs (60 °) is 150% or more in terms of gloss in the rolling parallel direction (based on JIS Z8741) of the surface formed by cold rolling. Rolled copper foil with excellent bending resistance.
(2) The rolled copper foil having a maximum height Ry (based on JIS B0601-1994) of 2.0 μm or less.
(3) The rolled copper foil having a flex fatigue life of 300,000 times or more in a flexible printed wiring board bending resistance test (based on JIS C5016) using test pieces collected in the rolling parallel direction.
(4) The rolled copper foil having a thickness of 35 μm or less.

  The present invention can produce a rolled copper foil having a high surface gloss by variously changing the final cold rolling conditions. As a result, it is possible to provide a rolled copper foil having excellent fatigue characteristics, high bending fatigue life, and small variations even under conditions in which minute irregularities on the rolled surface are controlled and a low strain bending load is repeatedly applied. In order to manufacture the rolled copper foil of the present invention, it is not necessary to add a new process and it is not necessary to add an alloy element, so that the manufacturing cost does not increase as compared with the conventional method.

In the rolled copper foil in the present invention, the sample was heated at 200 ° C. for 30 minutes, and the integral strength (I) of the (200) plane when obtained by X-ray diffraction of the rolled surface after heating, and the fine powder copper The I / I ₀ obtained from the measured value of the (200) plane integrated intensity (I ₀ ) satisfies the requirement of 20 or more. This is because when I / I ₀ is less than 20, the development of the (200) plane of the metal crystal on the surface is insufficient ((200) the degree of assembly is low), and the flex resistance deteriorates. The integrated intensity (I ₀ ) of the (200) plane of finely powdered copper was selected as a reference value for a state in which crystals were randomly oriented (a state in which a specific plane was not developed). The X-ray diffraction intensity of the rolled surface can be measured using, for example, an X-ray diffractometer RINT2000 manufactured by Rigaku Corporation. In Patent Document 1, the upper limit of I / I ₀ is not defined, but in the present invention, it is preferably 20 to 40. When I / I ₀ exceeds 40, the softening temperature of the rolled copper foil decreases. This is because a rolled copper foil having a remarkably low softening temperature is softened during storage at room temperature, and wrinkles are likely to occur, making handling difficult.

Usually, the maximum height Ry of the rolled copper foil surface on which deep oil pits are formed is higher than that on the surface on which shallow oil pits are formed. The depth of the oil pit has a correlation with the maximum height Ry (conforming to JIS B0601-1994) obtained from the surface roughness curve. Here, Ry is an index called “maximum height” defined in JIS B0601-1994.
The maximum height Ry (based on JIS B0601-1994) in the present invention is preferably 2.0 μm or less. This is because deep oil pits with Ry exceeding 2.0 μm cause a decrease in flexibility regardless of the density of oil pits. More preferably, it is 0.05 micrometer-1.5 micrometers. On the other hand, when Ry is less than 0.05 μm, when a plate subjected to roughening plating is bonded to a resin substrate, the adhesive strength between the two is reduced, which is not preferable. Since the oil pit is in the form of a crack perpendicular to the rolling direction, the measurement of the maximum height Ry with a contact roughness meter is important to scan the roughness stylus parallel to the rolling direction. For the observation of the form of the oil pit of the present invention, for example, an electron beam three-dimensional roughness analyzer ERA-8000 manufactured by Elionix Corporation can be used.
However, regarding the formation of oil pits, the bending resistance of the rolled copper foil is affected not only by the depth of the generated oil pits but also by the density, but in Ry, the density of oil pits affecting the bendability is accurate. Cannot be evaluated.

Therefore, in the present invention, paying attention to the fact that the density of the oil pits has a correlation with the glossiness of the surface, the glossiness was evaluated by measuring the glossiness according to JIS Z8741. The glossiness of the surface where the oil pits are formed at a low density shows a higher value than that of the surface where the oil pits are formed at a high density.
That is, the rolled copper foil of the present invention has a gloss in the rolling parallel direction (based on JIS Z8741) and Gs (60 °) of 150% or more, preferably 250% or more, more preferably 300% to 600%, most preferably. 400% to 600%.
When the glossiness Gs (60 °) of the rolled copper foil surface is less than 150, (1) there are many areas where oil pits exist, (2) the depth of oil pits is deep, (3) the oil pit density is high High (4) Due to the large number of minute irregularities that make up the surface including irregularities other than oil pits, the portion that becomes the starting point of cracks increases when bending deformation is repeatedly applied, and in the bending resistance test (conforming to JIS C5016) The life evaluation of is inferior.
On the other hand, if the glossiness Gs (60 °) of the rolled surface exceeds 600%, the surface of the metallic luster becomes less uniform, and the appearance of the rolled copper foil in the FPC processing process becomes poor. Preferably not. When the glossiness Gs (60 °) of the rolled surface exceeds 600%, the uniformity of the metallic luster is reduced because the density of oil pits is extremely low, and the distribution of minute irregularities other than oil pits is reflected in the appearance. By being done. The minute irregularities other than the oil pits are irregularities that existed before the rolling and are not completely lost in the subsequent cold rolling, but remain after changing the form. The unevenness | corrugation formed by the pickling performed after the annealing before final cold rolling is mentioned. In pickling, the oxide film and metallic copper produced by annealing are eluted and unevenness occurs, but in particular, the crystal grain boundaries are preferentially eluted and groove-like unevenness occurs. Also, buffing after pickling causes irregularities as polishing eyes. And these minute irregularities remaining after rolling are not uniformly distributed within the surface of the rolled copper foil, that is, the uniformity of the metallic luster is lowered, causing the appearance defect (streaks, unevenness, spots, etc.) Become.
The glossiness can be measured at an incident angle of 60 degrees in a direction parallel to the rolling direction in accordance with JIS Z8741.

The rolled copper foil of the present invention is produced by, for example, hot rolling a tough pitch copper, an oxygen-free copper ingot or Ag-containing copper, then repeating cold rolling and annealing, and finally performing final cold rolling.
And the state which forms an oil pit changes by changing final cold rolling conditions variously. For example, when the oil film introduced between the roll and the material at the time of final cold rolling is thick, the shear band due to plastic deformation of the material forms an oil pit on the rolling surface. If the oil film is thin, the convex portion of the material surface comes into contact with the roll, so that deformation is limited, and oil pits do not develop and a smooth surface is formed. By suppressing the growth of the oil pit and widening the area with few oil pits, a highly glossy copper foil surface can be obtained.
Therefore, in the production of the rolled copper foil of the present invention, the thickness of the oil film introduced between the roll and the material is controlled by the shape of the rolling roll, the rolling oil viscosity, and the rolling speed, and the density and depth of the oil pits are controlled. Is adjusted to produce a rolled copper foil having a desired glossiness and a preferred maximum height Ry. Specific conditions for setting the rolling roll diameter, rolling roll surface roughness, rolling roll viscosity, and rolling speed in the final cold rolling to produce a rolled copper foil having the desired glossiness and preferred maximum height Ry are as follows: Indicate.

These individual setting conditions are satisfied when other setting conditions are within the following setting conditions, and are not satisfied independently by ignoring the other setting conditions. Moreover, since these setting conditions take unique values depending on the rolling mill, they do not limit the scope of the present invention.
In the final cold rolling in the present invention, a rolling roll preferably having a roll diameter of 50 mm to 100 mm and a surface roughness Ra (arithmetic average roughness Ra, conforming to JIS B0601-1994) adjusted to 0.05 to 0.10 μm. use. If the rolling roll diameter exceeds 100 mm, the oil film introduced between the roll and the material at the time of final cold rolling becomes thick, oil pits are easily formed, and the density of oil pits increases. On the other hand, when the rolling roll diameter is less than 50 mm, the oil film introduced between the roll and the material at the time of final cold rolling becomes thin, and the density of oil pits becomes extremely low. If the density of the oil pits is extremely low, the uniformity of the metallic luster is lowered, and the appearance is poor in the process of processing the rolled copper foil into FPC. Also, if the surface roughness Ra of the rolling roll exceeds 0.10 μm, the oil film introduced between the roll and the material at the time of the final cold rolling becomes thick, oil pits are easily formed, and the density of oil pits is high. Become. On the other hand, when the surface roughness Ra of the rolling roll is less than 0.05 μm, the oil film introduced between the roll and the material at the time of final cold rolling becomes thin, and the density of oil pits becomes extremely low. If the density of the oil pits is extremely low, the uniformity of the metallic luster is lowered, and the appearance is poor in the process of processing the rolled copper foil into FPC.

The viscosity of the rolling oil used in the final cold rolling of the present invention is preferably 1 to 7 cSt. If it is 7 cSt or more, the oil film introduced between the roll and the material at the time of final cold rolling becomes thick, and oil pits are easily formed. On the other hand, if it is less than 1 cSt, the oil film introduced between the roll and the material at the time of final cold rolling becomes thin, and the density of oil pits becomes extremely low. If the density of the oil pits is extremely low, the uniformity of the metallic luster is lowered, and the appearance is poor in the process of processing the rolled copper foil into FPC.
The final cold rolling speed is preferably 100 to 400 m / min. If it exceeds 400 m / min, the oil film introduced between the roll and the material at the time of final cold rolling becomes thick, and oil pits are easily formed. On the other hand, if it is less than 100 m / min, the oil film introduced between the roll and the material at the time of final cold rolling becomes thin, and the density of oil pits becomes extremely low. If the density of the oil pits is extremely low, the uniformity of the metallic luster is lowered, and the appearance is poor in the process of processing the rolled copper foil into FPC.
The rolling degree of the final cold rolling of the present invention is preferably 90 to 99%, more preferably 95 to 99%. When the rolling degree is less than 90%, the development of the cube texture ((100) plane, <001> direction, (100) plane and (200) plane is equivalent) after heating at a temperature at which recrystallization occurs is performed. Since it is inferior, it is inferior in bending resistance, and when it exceeds 99%, pinholes are likely to occur in the final cold rolling.

The rolled copper foil of the present invention has an integrated intensity ratio I / I _{0 of} (200) plane of 20 or more and a surface glossiness Gs of 150% measured under predetermined conditions. The manufacturing procedure could not be achieved at the same time. For example, in Patent Document 1 which is the background art of the present invention, the annealing immediately before the final cold rolling is performed under the condition that the average grain size of the recrystallized grains is 5 to 20 μm, and the rolling work degree in the final cold rolling is By setting the ratio to 90% or more, I / I ₀ has achieved 20 or more. Usually, when the rolling speed is high, the viscosity of the rolling oil is lowered so that the oil film introduced between the roll and the material spreads uniformly, and when the rolling speed is slow, the oil film becomes thin so that the oil film does not break. In addition, it is necessary to increase the viscosity of the rolling oil. For this reason, the combination of the rolling speed and the rolling oil viscosity normally employed in the final cold rolling (rolling degree of 90% or more) of Patent Document 1 and the like is a rolling speed of 400 to 800 m / min, a rolling oil viscosity of 1 to 1. 7 cSt. On the other hand, when the rolling degree is 90% or more and the rolling speed is 100 to 400 m / min, it is necessary to increase the rolling oil viscosity, so the combination of the rolling oil viscosity of 7 to 13 cSt is appropriate. However, the rolling of a foil having a thickness of 35 μm or less under these conditions cannot be employed because the rolling speed is slow and the productivity is significantly reduced and the cost is increased. According to the research by the present inventors, even if the combination of the rolling speed and the rolling oil viscosity is 90% or higher and the integrated strength ratio I / I ₀ 20 or higher can be achieved by the combination of the rolling speed and the rolling oil viscosity, As a result, the surface glossiness Gs of 150% cannot be obtained. It was also found that in order to increase the surface glossiness, it is necessary to suppress the formation of oil pits, and the rolling degree should be set to a low value of less than 90%. However, when the rolling degree is set to a low value of less than 90%, the integrated strength ratio I / I ₀ is less than 20 because the rolling degree is low.
The present invention is aimed at a method for suppressing the formation of oil pits by changing rolling conditions while maintaining a rolling degree of 90% or more in order to achieve a specific integral intensity ratio and surface gloss at the same time. Contrary to conventional technical common sense regarding rolling speed and rolling oil viscosity, a low rolling oil viscosity of 1 to 7 cSt is preferably used even when a slow rolling speed of 100 to 400 m / min is adopted in the final cold rolling.

In the present invention, in addition to setting the final cold rolling conditions as described above, preferably the deep oil pits are formed by setting the average grain size of the recrystallized grains to 20 μm or less in the annealing before the final cold rolling. No rolling surface. When the average grain size of the recrystallized grains in the annealing before the final cold rolling exceeds 20 μm, a rolled surface having deep oil pits is formed. In order to set the average grain size of the recrystallized grains to 20 μm or less, for example, when annealing is performed in a continuous annealing furnace, heating is performed at a temperature of 500 to 800 ° C. for 5 to 600 seconds depending on the temperature, and the annealing is batch-processed. When performing by a formula, it heats for 1 to 24 hours at the temperature of 130-500 degreeC depending on the said temperature.
Further, since it is desired to reduce the thickness of the rolled copper foil as a material due to downsizing and low profile of electronic device parts in recent years, and high flexibility is desired, the thickness after the final cold rolling of the present invention is preferably Is more effective at 50 μm or less, more preferably 35 μm or less, and most preferably 18 μm or less.

When the rolled copper foil of the present invention satisfies the above requirements, in a flexible printed wiring board bending resistance test (compliant with JIS C5016) using test pieces taken in the rolling parallel direction, the bending fatigue life is 17 μm. Has a bending resistance of 100,000 times or more, preferably 200,000 times or more, and more preferably 300,000 times or more, and is excellent for conditions where a relatively gentle low strain bending load with a radius of curvature r is repeatedly applied. Shows tolerance. Therefore, the rolled copper foil of the present invention is useful as a rolled copper foil used for FPC.
The rolled copper foil of the present invention is used as an FPC constituent member in a softened state by heating. Therefore, the material of the rolled copper foil of the present invention includes, for example, normal tough pitch copper (oxygen concentration of 100 to 500 mass ppm) or oxygen-free copper (oxygen concentration of 10 mass ppm or less) that does not have a very high softening temperature, softening at room temperature storage In order to prevent this, tough pitch copper (Japanese Patent Laid-Open No. 2000-212661) whose softening temperature is adjusted to an appropriate range by adding a small amount of Ag or the like, a small amount of alloying elements is added for the purpose of lowering the softening temperature. It is possible to use materials such as oxygen-free copper (Japanese Patent No. 1582981 etc.) and oxygen-free copper (Japanese Patent Laid-Open No. 1-319641 etc.) whose softening temperature is adjusted to an appropriate range by adjusting the amount of impurities.

Hereinafter, an example of an embodiment of the present invention will be described.
Hot rolling using 200mm thick and 600mm wide tough pitch copper ingot (oxygen content 200ppm), oxygen free copper ingot (oxygen content less than 10ppm) and copper containing Ag (Ag content 200ppm, oxygen content 200ppm) Later, cold rolling and annealing were repeated to obtain a plate (thickness t mm) having a predetermined thickness after rolling. This plate was annealed in a heating furnace maintained at a temperature of 180 ° C. for 2 hours and cold-rolled to 17 μm.
Here, the rolling work degree R in the final cold rolling is given by R = (t−0.017) / t × 100 (%). The crystal grain size after annealing was measured by a cutting method based on JIS G0551 in a cross section perpendicular to the rolling direction. The average grain size of recrystallized grains obtained by annealing before the final cold rolling was 15 μm, the diameter of the rolling roll used for the final cold rolling was 100 mm, and the surface roughness Ra of the rolling roll was 0.10 μm. Further, the degree of development (I / I ₀ ) of the cube texture was changed by controlling the rolling degree of the final cold rolling.
In this production method, (1) the annealing temperature before the final cold rolling, and (2) the rolling conditions (rolling speed, rolling workability, rolling oil viscosity) of the final cold rolling are variously changed, and Invention Example 1 To 6 and Comparative Examples 1 to 14 were obtained.

The following characteristics were evaluated about the rolled copper foil of the invention example and the comparative example.
(1) Glossiness Gs (60 °)
Using a gloss meter in accordance with JIS Z8741, the gloss was measured at an incident angle of 60 degrees in a direction parallel to the rolling direction.
(2) Cube texture (I / I ₀ )
After heating the sample at 200 ° C. for 30 minutes, an integral value (I) of the 200-plane strength was determined by X-ray diffraction of the rolled surface using an X-ray diffractometer RINT2000 manufactured by Rigaku Corporation. This value was divided by the integral value (I ₀ ) of the (200) plane strength of finely powdered copper that had been measured in advance, and the value of I / I ₀ was calculated. In addition, the measurement of the integrated value of peak intensity was performed in the range of 2 (theta) = 57-63 degrees ((theta) is a diffraction angle) using Co tube. This measurement was performed twice at different measurement positions, and the average value was obtained. In the following, I / I ₀ is referred to as the 200-plane aggregation degree.
(3) Maximum height (Ry)
Based on JIS B0601-1994, the measurement was performed under the conditions of a reference length of 0.8 mm, an evaluation length of 4 mm, a cut-off value of 0.8 mm, and a feed speed of 0.1 mm / second. This measurement was performed 10 times in parallel with the rolling direction while changing the measurement position, and the maximum value in 10 measurements was obtained.
(4) Bending resistance After heating the sample at 200 ° C. for 30 minutes, an FPC bending resistance test based on JIS C5016 was performed to measure the bending fatigue life. Specifically, the bending fatigue life was measured with the apparatus shown in FIG. This apparatus has a structure in which a vibration transmission member 3 is coupled to an oscillation driver 4, and the tested rolled copper foil 1 has a total of four points including a screw 2 portion indicated by an arrow and a tip portion of the vibration transmission member 3. Fixed to the device. When the vibration transmitting member 3 is driven up and down, the intermediate portion of the rolled copper foil 1 is bent into a hairpin shape with a predetermined radius of curvature r.
In this test, the number of times until fracture in the accelerated test in which bending was repeated under the following conditions was determined. Specimen width 12.7 mm, Specimen length: 200 mm, Specimen sampling direction: Collected so that the length direction of the specimen is parallel to the rolling direction, Curvature radius r: 2.5 mm, No tensile load applied, Vibration stroke : 25 mm, vibration speed: 1500 times / min. This is a more severe condition than the condition in which FPC is actually used. The measurement was performed 5 times for the same material, and the average value was obtained.

Table 1 shows the rolling conditions and measurement results of the inventive examples and comparative examples.
Invention Examples 1-4 and Comparative Examples 1-12 were implemented about the rolled copper foil whose thickness is 17 micrometers. In Invention Examples 1 to 4, since the degree of rolling work in the final cold rolling is in an appropriate range, the degree of 200-side assembly is in the range of the present invention, and the rolling speed and rolling oil viscosity in the final cold rolling are preferable. Therefore, the glossiness is within the scope of the present invention. As a result, Inventive Examples 1 to 4 have a longer bending fatigue cycle life (number of times) than Comparative Examples 1 to 12, and all exceed 300,000 times. On the other hand, in Comparative Examples 1 to 4, the rolling speed and the rolling oil viscosity are out of the preferred ranges, so the glossiness is below the range of the present invention. In Comparative Examples 5 to 12, the degree of rolling is outside the preferred range, so the degree of 200-plane aggregation is below the range of the present invention. As a result, Comparative Examples 1 to 12 have less flexural fatigue cycle life than Inventive Examples 1 to 4, which is less than 300,000 times, Comparative Examples 1 to 8 are less than 200,000 times, and Comparative Examples 5 to 8 are particularly 10 Less than 10,000 times.
Inventive Examples 1-4 and Comparative Examples 9-12 all have a rolling speed of 100-400 m / min and a rolling oil viscosity of 1-7 cSt, but Inventive Examples 1-4 are glossy compared to Comparative Examples 9-12. Is low. This is because Invention Examples 1 to 4 have a higher degree of rolling than Comparative Examples 9 to 12.

In Invention Examples 1 and 2, not only the glossiness and the degree of aggregation of 200 planes are within the range of the present invention, but also the crystal grain size and the rolling workability in the annealing before rolling are within the preferable ranges, so the maximum height Ry Is within the preferred range of the present invention. As a result, Invention Examples 1 and 2 have the longest bending fatigue cycle life among Invention Examples 1-6.
On the other hand, in Invention Examples 3 and 4, the glossiness and the degree of aggregation of 200 planes are within the range of the present invention, but the crystal grain size in the annealing before the final cold rolling exceeds the preferred range, so the maximum height Ry is The preferred range of the present invention is exceeded. As a result, Invention Examples 3 and 4 have a shorter bending fatigue cycle life than Invention Examples 1 and 2.
Invention Examples 5 and 6 were carried out on rolled copper foils having thicknesses of 33 μm and 66 μm. In Invention Examples 5 and 6, since the rolling speed, rolling oil viscosity, crystal grain size in annealing before rolling, and rolling degree are within preferable ranges, the glossiness and the degree of aggregation of 200 planes are only within the scope of the present invention. In addition, the maximum height Ry is also within the preferred range of the present invention. Therefore, Invention Examples 5 and 6 have a thick bending fatigue cycle life as compared with Invention Examples 1 to 4 because they are thick, but have a longer bending fatigue cycle life than Comparative Examples 13 and 14 of the same thickness. Can be confirmed.

In Comparative Examples 1 and 2, since the rolling speed and rolling oil viscosity in the final cold rolling exceed the preferred ranges, the glossiness is outside the range of the present invention, but the crystal grains in the annealing before the final cold rolling. Since the diameter and the rolling degree are within the preferable ranges, the degree of 200-side assembly is within the range of the present invention, and the maximum height Ry is within the preferable range of the present invention. As a result, Comparative Examples 1 and 2 have a shorter bending fatigue cycle life than Invention Examples 1 to 4 and Comparative Examples 9 to 12, but are the largest among Comparative Examples 1 to 8.
In Comparative Examples 3 and 4, since the gloss is below the range of the present invention and the crystal grain size in the annealing before the final cold rolling is outside the preferred range, the maximum height Ry exceeds the preferred upper limit of the present invention. Yes. As a result, Comparative Examples 3 and 4 have less bending fatigue cycle life than Comparative Examples 1 and 2 as well as Invention Examples 1 to 4.
In Comparative Examples 5 and 6, the rolling speed and rolling oil viscosity in the final cold rolling exceeds the preferable upper limit, and the rolling degree is less than the preferable range, so the glossiness and the 200-plane aggregation degree are within the scope of the present invention. It is below. As a result, the bending fatigue cycle life of Comparative Examples 5 and 6 is less than Invention Examples 1 to 4, and is even less than Comparative Examples 1 to 4.

In Comparative Examples 7 and 8, the rolling speed and rolling oil viscosity in the final cold rolling exceeds the preferable ranges, and the crystal grain size and the rolling work degree in the annealing before the final cold rolling are outside the preferable ranges. And the degree of assembly of 200 planes is below the range of the present invention, and the maximum height Ry is outside the preferred range of the present invention. As a result, the bending fatigue cycle life of Comparative Examples 7 and 8 is less than Comparative Examples 1 to 6 as well as Invention Examples 1 to 4.
In Comparative Examples 9 and 10, since the rolling speed and rolling oil viscosity in the final cold rolling are within a preferable range, the glossiness is within the range of the present invention, but the rolling degree is below the preferable range, The degree of 200-plane assembly is below the scope of the present invention. As a result, Comparative Examples 9 and 10 have a shorter bending fatigue cycle life than Invention Examples 1 and 2.
In Comparative Examples 11 and 12, since the rolling speed and rolling oil viscosity in the final cold rolling are within the preferred ranges, the glossiness is within the scope of the present invention, but the crystal grain size and rolling in the annealing before the final cold rolling Since the degree of processing is outside the preferred range, the degree of 200-plane assembly is less than the range of the present invention, and the maximum height Ry is outside the preferred range of the present invention. As a result, Comparative Examples 11 and 12 have a shorter bending fatigue cycle life than Invention Examples 1 to 4, and are lower than Comparative Examples 9 and 10.
Comparative Examples 13 and 14 were carried out for thicknesses of 33 μm and 66 μm. Since the rolling speed and rolling oil viscosity in the final cold rolling exceeded the preferable ranges, the glossiness was below the range of the present invention. As a result, Comparative Examples 13 and 14 have a shorter bending fatigue cycle life than Invention Examples 5 and 6. Furthermore, since Comparative Examples 13 and 14 are thick, the flex fatigue cycle life is less than Comparative Examples 1-12. In particular, Comparative Example 14 had a bending fatigue cycle life at the lowest level because the thickness was outside the preferred range of the present invention.

It is the schematic of the FPC bending resistance test apparatus based on JISC5016.

Claims (3)

After heating at 200 ° C. for 30 minutes, the ratio I / I ₀ of the integrated intensity (I) of the (200) plane determined by X-ray diffraction of the rolled surface to the integrated intensity (I ₀ ) of the (200) plane of finely powdered copper There the rolled copper foil is 20 or more, parallel to the rolling direction of the gloss of the cold-rolled at the surface formed (JIS Z8741 compliant) with Gs (60 °) is Ri der least 150%, the maximum height Ry (JIS rolled copper foil B0601-1994 compliant) and excellent bending resistance, characterized in der Rukoto below 2.0 .mu.m. Rolled copper foil in the direction parallel to the rolling direction in the collected specimen flexible printed wiring board flex resistance test using (JIS C5016 compliant), according to claim 1 Symbol placement flex fatigue life is more than 300,000 times. The rolled copper foil according to claim 1 or 2 , wherein the thickness is 35 µm or less.

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