JP2013189702A - Rolled copper foil and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent softening at normal temperature and withstand long-term storage while keeping such a state where high flexural property due to recrystallization can be given.SOLUTION: A rolled copper foil is used for a flexible printed wiring board and contains oxygen (O), sulfur (S), silver (Ag), and iron (Fe) with predetermined concentrations. The rolled copper foil is subjected to hot rolling step at predetermined temperature, and a specified value Tdefined by formula, T=-98[O]+1840[S]+2005[Ag]-824[Fe]+0.012Tr, is 9.8 or more (where [E] is the concentrations (mass%) of elements E included in the rolled copper foil, and Tr is temperature (°C) in the hot rolling step).

Description

  The present invention relates to a rolled copper foil and a rolled copper foil manufacturing method, and more particularly to a rolled copper foil used for a flexible printed wiring board and a rolled copper foil manufacturing method.

  In the field of flexible printed circuit (FPC), copper foil is laminated to an insulating resin substrate made of polyimide resin film, etc., or polyimide precursor is applied onto another copper foil and dried. It has been used as a conductor layer by bonding to the surface of a cured insulating resin substrate. A resin base material having such a copper foil is called a copper-clad board, and the copper foil serving as a conductor layer is processed into a predetermined wiring pattern by using, for example, a photolithography method or an etching method, thereby enabling flexible printing. A wiring board is manufactured.

  In many cases, a rolled copper foil having excellent bending characteristics is used as the copper foil used for the flexible printed wiring board. This is because the flexible printed wiring board is often used for a member that is repeatedly bent, such as a printer head, a drive in a hard disk, or a hinge of a clamshell type mobile phone.

  A rolled copper foil is produced by hot rolling an ingot produced by casting, then repeating a cold rolling process and an annealing process for removing strain, and reducing the thickness to a predetermined thickness after the final annealing process. . Then, in order to ensure adhesiveness with a resin base material etc., a roughening process and a rust prevention process are given to the surface of rolled copper foil, for example.

  In order to obtain the high bending characteristic that is a feature of the rolled copper foil, for example, when the rolled copper foil manufactured as described above is bonded to a resin substrate, it is heated to recrystallize and soften the crystal structure. The reason why softening is not performed during the production of the rolled copper foil is that the rolled copper foil may be deformed or wrinkled when bonded to the resin base material. Therefore, rolled copper foil (hereinafter also referred to as tough pitch copper foil) made of tough pitch copper having a relatively low softening temperature among the rolled copper foils so that softening easily occurs by heating at the time of bonding with the resin base material. Often used.

  On the other hand, as raw materials for rolled copper foil, oxygen-free copper and various alloys exist in addition to tough pitch copper. These have a higher softening temperature than tough pitch copper and may not be softened even by heating during bonding to the resin base material. Therefore, for example, in order to adjust the softening temperature of oxygen-free copper, the conditions of the manufacturing process are changed (for example, Patent Document 1), a special metal is added (for example, Patent Document 2), or the concentration of a trace amount of impurities Countermeasures have been proposed (for example, Patent Document 3).

JP-A-01-212739 JP 59-159954 A JP 2000-212660 A

  The bending characteristics of the rolled copper foil such as the tough pitch copper foil are improved as the cubic structure is more present in the recrystallized structure. In order to make many cube structures exist, for example, in the manufacturing process of rolled copper foil, there is a method of increasing the degree of processing after the final annealing process.

  However, the tough pitch copper foil manufactured by the method as described above has a markedly lowered softening temperature due to an increase in plastic strain accumulated by rolling, and softening occurs for a long time even when stored at room temperature. There was a case. This phenomenon is called room temperature softening. In the tough pitch copper foil, for example, the semi-softening temperature by heating for 30 minutes is relatively low at 120 ° C. to 150 ° C., and such normal temperature softening frequently occurs and the quality may be deteriorated.

  Specifically, in the crystal structure of the tough pitch copper foil that has been softened at room temperature, there are partially coarse recrystallized grains in the rolled structure, which is a so-called mixed grain state. That is, a high strength portion and a low strength portion are mixed in the surface of the tough pitch copper foil. In such a state, wrinkles are likely to occur during bonding with the resin base material, and burrs are likely to occur during subsequent cutting (slit processing). In addition, the recrystallized grains generated by softening at room temperature are often not a cubic structure, and the bending characteristics may be adversely affected.

Considering transportation after manufacture and storage period for users, it is preferable to maintain a tensile strength of 300 N / mm ² or more even when stored for one year at 30 ° C. as a quantitative guideline for the influence of softening at room temperature. This corresponds to the tensile strength after heating at 100 ° C. for 4 hours in the accelerated test.

  In addition, as described in Patent Documents 1 to 3 above, with respect to a technique for using oxygen-free copper or the like having a softening temperature higher than that of tough pitch copper and performing various adjustments so as to be softened by heating at the time of bonding with a resin base material. However, none of them has been adopted mainly because of cost problems.

  An object of the present invention is to provide a rolled copper foil that can withstand long-term storage while suppressing softening at room temperature and maintaining high bending characteristics by recrystallization, and a method for producing the rolled copper foil.

According to a first aspect of the invention,
It is a rolled copper foil used for flexible printed wiring boards,
A predetermined concentration of oxygen (O), sulfur (S), silver (Ag), iron (Fe) is contained, a hot rolling process is performed at a predetermined temperature, and a specified value T _N defined by the following formula is A rolled copper foil having a surface area ratio of 9.8 or more, a (200) plane area ratio of 20 or more, and a thickness of 5 μm or more and 50 μm or less is provided.
T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr
(Here, [E] is the concentration (mass%) of element E contained in the rolled copper foil, and Tr is the temperature (° C.) in the hot rolling step.)

According to a second aspect of the invention,
The oxygen concentration [O] is 0.0001% by mass or more and 0.1% by mass or less,
The sulfur concentration [S] is 0.0001 mass% or more and 0.01 mass% or less,
The silver concentration [Ag] is 0.0001 mass% or more and 0.01 mass% or less,
The iron concentration [Fe] is 0.0001 mass% or more and 0.003 mass% or less,
The rolled copper foil as described in the 1st aspect whose temperature Tr in the said hot rolling process is 700 degreeC or more and 1000 degrees C or less is provided.

According to a third aspect of the invention,
The total concentration of arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), nickel (Ni), lead (Pb), and silicon (Si) contained is 0.02% by mass or less. The rolled copper foil as described in the 1st or 2nd aspect is provided.

According to a fourth aspect of the invention,
The final annealing process has been applied,
The rolled copper foil in any one of the 1st-3rd aspect whose workability after the said last annealing process is 80% or more and less than 97% is provided.

According to a fifth aspect of the present invention,
A method for producing a rolled copper foil used in a flexible printed wiring board,
A hot rolling process in which hot rolling is performed at a predetermined temperature on a copper ingot containing oxygen (O), sulfur (S), silver (Ag), and iron (Fe) at a predetermined concentration; and a final annealing process. Have
A prescribed value T defined by the following equation by controlling the concentration of each element and the temperature in the hot rolling step
_N is not less than 9.8, and
A process for producing a rolled copper foil in which the thickness of the rolled copper foil is 5 μm or more and 50 μm or less is provided by a process in which the degree of work after the final annealing step is 80% or more and less than 97%.
T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr
(Here, [E] is the concentration (mass%) of element E contained in the rolled copper foil, and Tr is the temperature (° C.) in the hot rolling step.)

According to a sixth aspect of the present invention,
It is a rolled copper foil used for flexible printed wiring boards,
Contains oxygen (O), sulfur (S), silver (Ag), iron (Fe) at a predetermined concentration,
The (200) plane area ratio is 20 or more,
The tensile strength is 300 N / mm ² or more, and
A rolled copper foil having a thickness of 5 μm to 50 μm is provided.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the rolled copper foil which suppresses normal temperature softening and withstands a long-term storage, and the state which can provide the high bending characteristic by recrystallization is provided.

It is a flowchart which shows the manufacturing process of the rolled copper foil which concerns on one Embodiment of this invention. It is a figure which shows the outline | summary of the tension test of the rolled copper foil which concerns on the Example of this invention. It is a schematic diagram of the sliding bending test apparatus which measures the bending characteristic of the rolled copper foil which concerns on the Example of this invention.

<Knowledge obtained by the present inventors>
A rolled copper foil made of such tough pitch copper as a raw material contains a plurality of various impurity elements. Among such impurity elements, for example, the concentration of oxygen (O), sulfur (S), silver (Ag), and iron (Fe) greatly affects the likelihood of softening at room temperature. On the other hand, these elements are mainly mixed in the manufacturing process of tough pitch copper as a raw material, and the concentration can be controlled relatively easily. Therefore, by controlling the concentration of each of these elements, a predetermined effect can be obtained with respect to suppression of softening at room temperature.

  However, other than the above, rolled copper foil such as arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), nickel (Ni), lead (Pb), silicon (Si), etc. There are many impurity elements that are contained therein and can affect the softening at room temperature. For this reason, only controlling the concentration of each element may cause sudden room temperature softening due to other impurity elements. Nevertheless, it is difficult to individually manage all the concentrations of these minute impurity elements from the standpoint of cost.

  Therefore, the present inventors have examined various other factors that can affect the softening at room temperature. As a result of such diligent research, the inventors of the present invention control the concentration of O, S, Ag, and Fe, and also control the temperature in the hot rolling process that has a great influence on softening at room temperature. For example, the inventors have found that the effects of trace impurity elements other than the above can be ignored.

  In addition, the present inventors investigated the degree of influence on normal temperature softening due to the concentration of each element and the temperature in the hot rolling process. Specifically, the composition of the tough pitch copper ingot (ingot) and the temperature in the hot rolling process were variously combined to evaluate the ease of softening at room temperature. As a result, the present inventors have identified the correlation between each factor such as the concentration of the element and the temperature in the hot rolling process and the degree of influence of each factor on normal temperature softening.

  The present invention is based on the above findings found by the inventors.

<One Embodiment of the Present Invention>
(1) Configuration of Rolled Copper Foil First, the configuration of the tough pitch copper foil as a rolled copper foil according to an embodiment of the present invention will be described.

  The tough pitch copper foil according to the present embodiment is a rolled copper foil using, for example, tough pitch copper as a raw material and subjected to a hot rolling process at a predetermined temperature, and is used as a conductor layer of a flexible printed wiring board. The tough pitch copper used as a raw material is a copper material having a purity specified in JIS C1100, H3100, etc. of 99.9% or more.

The tough pitch copper foil includes a plurality of impurity elements having a predetermined concentration, for example. Regarding the concentrations of oxygen (O), sulfur (S), silver (Ag), and iron (Fe) among such impurity elements, along with the temperature in the hot rolling process applied to the tough pitch copper foil, Control is performed so that the prescribed value T _N defined by the equation (1) is 9.8 or more.

T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr (1)

  Here, [E] is the concentration (mass%) of the element E contained in the tough pitch copper foil, and Tr is the temperature (° C.) in the hot rolling process.

The above equation (1) calculates the correlation between each factor such as the concentration of the element and the temperature in the hot rolling process and the degree of influence of each factor on normal temperature softening as a proportional relationship, and the influence of each factor. The specified value T _N is defined by adding a coefficient for weighting the degree.

That is, in Equation (1), when the oxygen concentration [O] and the Fe concentration [Fe] to which negative coefficients are added are low, softening at room temperature is suppressed. Specifically, oxygen in the tough pitch copper foil is easily combined with copper (Cu) and other impurities in the tough pitch copper foil to form an oxide. When the oxygen concentration [O] or Fe concentration [Fe] in the tough pitch copper foil is low, it is difficult to combine oxygen and Fe, so formation of FeO ₄ as a starting point of softening is suppressed, and normal temperature softening is suppressed. The

Further, when the S concentration [S], the Ag concentration [Ag], and the temperature Tr in the hot rolling process to which a positive coefficient is applied are high, softening at room temperature is suppressed. In general, eutectic type alloys exhibit high heat resistance. When the S concentration [S] and the Ag concentration [Ag] in the tough pitch copper foil are high, Cu—Cu ₂ S eutectic and Cu—Ag eutectic are likely to be formed, and softening at room temperature is suppressed.

  Furthermore, considering the concentration of each element that can be contained in the raw material tough pitch copper and the temperature that can be applied to the hot rolling process naturally have a reasonable range, the concentration of each element and the hot rolling process The temperature is preferably in the following range, for example.

  That is, for example, the oxygen concentration [O] contained in the tough pitch copper foil is 0.0001 mass% or more and 0.1 mass% or less, and the S concentration [S] is 0.0001 mass% or more and 0.01 mass%. %, The Ag concentration [Ag] is 0.0001 mass% or more and 0.01 mass% or less, and the Fe concentration [Fe] is 0.0001 mass% or more and 0.003 mass% or less. For example, the temperature Tr in the hot rolling process is 700 ° C. or higher and 1000 ° C. or lower.

Preferably, the prescribed value T _N can be set to 9.8 or more by controlling either the concentration of each element or the temperature in hot rolling, or both within the above range.

  Examples of impurities other than those described above include arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), nickel (Ni), lead (Pb), and silicon (Si). Is mentioned. The total concentration of these impurity elements other than the above is, for example, 0.02% by mass or less.

Moreover, the thickness of the said tough pitch copper foil is 5 micrometers or more and 50 micrometers or less, for example. The tough pitch copper foil is subjected to a final annealing step in addition to the hot rolling step, and the predetermined thickness is obtained by processing such that the degree of processing after the final annealing step is 80% or more and less than 97%. Yes. Here, the processing degree is defined as T ( _B) , where T _B is the thickness of the workpiece before processing, and T _A is the thickness after processing, and the processing degree (%) = [(T _B −T _A ) / T _B ]. It is represented by x100.

  As described above, in the present embodiment, rolled copper foil is employed as the conductor layer used for the flexible printed wiring board. Thereby, a high bending characteristic can be provided to rolled copper foil by passing through the recrystallization annealing process mentioned later.

  Moreover, in this embodiment, it can be softened at a relatively low temperature by applying a tough pitch copper foil whose raw material is tough pitch copper. Therefore, for example, when used as a conductor layer of a flexible printed wiring board, it can be recrystallized by heating at the time of bonding with a resin substrate.

In this embodiment, the concentration of O, S, Ag, and Fe contained in the tough pitch copper foil and the temperature in the hot rolling process are determined according to the specified value T _N defined by the equation (1). I have control. Thereby, it can be set as the tough pitch copper foil which suppresses softening at normal temperature and withstands long-term storage while maintaining a state in which high bending characteristics can be imparted by recrystallization.

  That is, as described above, even if there are uncertainties due to impurity elements such as As, Sb, Bi, Sn, Ni, Pb, and Si, the concentration of O, S, Ag, and Fe and the temperature in the hot rolling process By controlling the above, it is possible to suppress room temperature softening of the tough pitch copper foil. Therefore, the change in the crystal structure due to softening at room temperature can be suppressed, and it is possible to withstand long-term storage while substantially maintaining the state of the initial tough pitch copper foil to which high bending characteristics are imparted by recrystallization.

In the present embodiment, the total concentration of As, Sb, Bi, Sn, Ni, Pb, Si, and the like is not more than a predetermined value. Thereby, the inhibitory effect of normal temperature softening can be further enhanced. Specifically, for example, the tensile strength after heating at 100 ° C. for 4 hours is 300 N / mm ² or more.

  Moreover, in this embodiment, the thickness of the tough pitch copper foil is 5 μm or more and 50 μm or less by processing that the processing degree after the final annealing step is 80% or more and less than 97%. Thereby, many (200) planes which are cubic structures are obtained by recrystallization, and the bending characteristic provided to tough pitch copper foil can be improved further. Specifically, for example, the area ratio of the (200) plane per unit area after recrystallization by heating at 180 ° C. for 1 hour is 20% or more, preferably 40% or more.

(2) Manufacturing method of rolled copper foil Next, the manufacturing method of the tough pitch copper foil as rolled copper foil which concerns on one Embodiment of this invention is demonstrated using FIG. FIG. 1 is a flowchart showing a manufacturing process of a tough pitch copper foil according to the present embodiment.

(Ingot preparation step S10)
As shown in FIG. 1, first, casting is performed using tough pitch copper as a raw material to prepare an ingot. The ingot is formed in a plate shape having a predetermined thickness and a predetermined width, for example.

  The tough pitch copper used as a raw material is, for example, electrolytic copper manufactured by electrolytic refining and having a purity of 99.9%, and contains, for example, the above-mentioned predetermined concentrations of O, S, Ag, and Fe. The total concentration of As, Sb, Bi, Sn, Ni, Pb, Si, etc. contained in the tough pitch copper is not more than the predetermined value.

  The oxygen concentration [O] of the tough pitch copper is adjusted, for example, by subjecting dissolved electrolytic copper to a deoxidation step. S and Ag are contained as impurity elements in electrolytic copper from the beginning, and electrolytic copper having a predetermined S concentration [S] and Ag concentration [Ag] is selected from electrolytic copper having various compositions. be able to. Fe is included as an impurity element in electrolytic copper from the beginning, and is mixed in the deoxidation step. Therefore, a predetermined Fe concentration [Fe] can be obtained by selection of electrolytic copper, management of a deoxidation process, or the like.

(Hot rolling process S20)
In the hot rolling step, hot rolling is performed in which a tough pitch copper ingot containing the above-mentioned predetermined concentrations of O, S, Ag, and Fe is heated and held at the predetermined temperature for a predetermined time, for example, and then rolled. In this way, the ingot is subjected to a hot rolling step to obtain a plate material having a thickness smaller than a predetermined thickness after casting.

As described above, the specified value T _N defined by the above formula (1) is set to 9.8 or more by controlling the concentration of each element and the temperature in the hot rolling process. Here, the temperature in the hot rolling process is controlled in accordance with the concentration of each element contained in the tough pitch copper as the raw material so that a specified value _{TN of} 9.8 or more is obtained. Alternatively, when the temperature in the hot rolling process is determined in advance, tough pitch copper having a predetermined composition is selected so that a specified value T _{N of} 9.8 or more is obtained, or the tough pitch copper is intentionally used. A predetermined element may be added.

  Then, the oxide scale (black skin) on the surface of the plate material generated by heating in the hot rolling process is scraped off.

(Repetition step S30)
Subsequently, a repeating step S30 is performed in which the cold rolling step S31 and the annealing step S32 are repeatedly performed a predetermined number of times. That is, the plate material that has been cold-rolled and work hardened is subjected to an annealing treatment to anneal the plate material, thereby removing strain and relaxing work hardening. This is repeated a predetermined number of times so that the degree of processing becomes, for example, 50% to 90%, and a copper strip having a predetermined thickness is obtained.

  In addition, annealing process S32 performed at the last in repeating process S30 is called "final annealing process." After the final annealing step, the oxide scale (black skin) is removed.

(Final cold rolling process S40)
Next, the final cold rolling step S40 is performed, and the copper strip is processed so that the degree of processing after the final annealing step is 80% or more and less than 97%. At this time, the thickness of the copper strip is adjusted to, for example, 5 μm or more and 50 μm or less, and the thickness of the tough pitch copper foil obtained after manufacture is adjusted to be approximately 5 μm or more and 50 μm or less.

  The reason why the processing degree is set within the above range is as follows. When the degree of work is less than 80%, even if a recrystallization annealing process described later is performed, the area ratio of the (200) plane which is a cubic structure does not become 20% or more, for example, and sufficient bending characteristics cannot be obtained. On the other hand, at a workability of 97% or more, a great amount of plastic strain is accumulated in the copper strip, and the softening temperature is extremely lowered. For this reason, for example, recrystallization occurs due to heat of about the processing heat in the final cold rolling step, and the accumulated plastic strain is released. As a result, even if a recrystallization annealing process is performed, sufficient bending characteristics cannot be provided.

(Surface treatment step S50)
The copper strip that has undergone the above steps is subjected to predetermined surface treatments such as roughening treatment and rust prevention treatment to obtain a tough pitch copper foil having a thickness of 5 μm or more and 50 μm or less.

  By the adjustment in the final cold rolling step S40, sufficient strength can be obtained by setting the thickness of the tough pitch copper foil to 5 μm or more, and handling of the tough pitch copper foil becomes easy. In addition, when the tough pitch copper foil is too thick, even if the cubic structure is sufficiently developed, high bending characteristics cannot be obtained. Therefore, the thickness of the tough pitch copper foil is set to 50 μm or less.

  As described above, the tough pitch copper foil according to the present embodiment, which suppresses softening at room temperature and can withstand long-term storage while maintaining a state where high bending characteristics can be imparted by recrystallization, is manufactured.

(3) Manufacturing method of flexible printed wiring board Next, the manufacturing method of the flexible printed wiring board using the tough pitch copper foil which concerns on one Embodiment of this invention as a conductor layer is demonstrated.

(Recrystallization annealing process (CCL process))
First, the tough pitch copper foil according to the present embodiment is cut into a predetermined size and bonded to a resin base material made of a resin such as polyimide to form a copper clad plate (CCL: Copper Clad Laminate). At this time, any of a method of forming a three-layer material CCL that is bonded through an adhesive and a method of forming a two-layer material CCL that is directly bonded without using an adhesive may be used. When an adhesive is used, the adhesive is cured by heat treatment, and the tough pitch copper foil and the base material are brought into close contact with each other to be integrated. When no adhesive is used, it is brought into close contact by heating and pressing. The heating temperature and time can be appropriately selected according to the curing temperature of the adhesive and the substrate.

  Moreover, in this embodiment, the said CCL process which bonds a tough pitch copper foil to a resin base material serves as the recrystallization annealing process with respect to a tough pitch copper foil. That is, the tough pitch copper foil according to the present embodiment uses, for example, tough pitch copper having a relatively low softening temperature as a raw material. Therefore, the tough pitch copper foil is recrystallized and softened by the heating, and the bending characteristics of the tough pitch copper foil can be remarkably improved. On the other hand, in the process until the tough pitch copper foil is bonded to the resin base material, the tough pitch copper foil can be handled in a state before softening, and wrinkles and deformation when the tough pitch copper foil is bonded to the resin base material can be suppressed. .

(Surface machining process)
Next, a surface processing step is performed on the tough pitch copper foil as the conductor layer bonded to the resin base material. In the surface processing process, for example, a wiring forming process for forming copper wiring or the like on a tough pitch copper foil using a technique such as etching, and plating for improving the connection reliability between the copper wiring and another electronic member. A processing step and a protective film forming step of forming a protective film such as a solder resist so as to cover a part of the copper wiring to protect the copper wiring and the like are performed.

  As described above, the flexible printed wiring board using the tough pitch copper foil according to the present embodiment is manufactured.

<Other Embodiments of the Present Invention>
As mentioned above, although embodiment of this invention was described concretely, this invention is not limited to the above-mentioned embodiment, It can change variously in the range which does not deviate from the summary.

  For example, in the above-described embodiment, the degree of work in the final cold rolling step S40 is set to 80% or more to obtain excellent bending characteristics. However, the above-described embodiment suppresses normal temperature softening based on the above formula (1). The method of the embodiment can be used independently of this. By suppressing normal temperature softening, at least the state that the tough pitch copper foil was provided at the beginning of manufacture can be maintained, and deterioration of bending characteristics can be suppressed.

  Moreover, in the above-mentioned embodiment, although the CCL process in the manufacturing process of a flexible printed wiring board also served as the recrystallization annealing process with respect to a tough pitch copper foil, even if it performs a recrystallization annealing process as a separate process from a CCL process. Good.

  In the above-described embodiment, the tough pitch copper foil is used for the flexible printed wiring board. However, the use of the tough pitch copper foil is not limited to this. For example, the tough pitch copper foil is used as an electrode copper foil for a lithium ion secondary battery. Also good. Also about the thickness of a tough pitch copper foil, it can change suitably according to various uses including a flexible printed wiring board use.

  Next, examples according to the present invention will be described together with comparative examples.

(1) Manufacture of rolled copper foil First, the tough pitch copper foil which concerns on Examples 1-24, Comparative Examples AC, and Comparative Examples 1-7 was manufactured with the procedure and method similar to the above-mentioned embodiment. However, Comparative Examples A to C and Comparative Examples 1 to 7 intentionally include processing and numerical values that deviate from the predetermined value.

  In manufacturing each tough pitch copper foil, a plurality of ingots of tough pitch copper having different compositions were prepared, heated and held at a predetermined temperature for 200 minutes or more, and hot rolled to obtain a plate material having a thickness of 10 mm. At this time, a plurality of plate materials subjected to the hot rolling process at different temperatures were manufactured. Next, the tough pitches according to Examples 1 to 24, Comparative Examples A to C, and Comparative Examples 1 to 7 having different thicknesses and workability by performing the same repeating process and the final cold rolling process as described above on the respective plate materials. Copper foil was used.

(2) Measurement of rolled copper foil Next, the following measurements were performed on the tough pitch copper foils according to Examples 1 to 24, Comparative Examples A to C, and Comparative Examples 1 to 7.

(Measurement of tensile strength)
First, the tensile strength of each tough pitch copper foil was measured, and the degree of occurrence of softening at room temperature was quantitatively evaluated. Specifically, as an accelerated test in which each tough pitch copper foil having a width of 15 mm and a length of 200 mm cut out parallel to the rolling direction is exposed to the same state as stored at 30 ° C. for 1 year, at 100 ° C. in the atmosphere. Heated for 4 hours.

  Then, the tension test was done with respect to each tough pitch copper foil using Shimadzu Corporation autograph AGS-5kNX. That is, as schematically shown in FIG. 2, the upper fixing jig 11t and the lower fixing jig 11b fix both ends of the sample F (tough pitch copper foil) and are connected to the upper fixing jig 11t and connected to the upper fixing jig. A cross head (not shown) located above the tool 11t was driven upward (in the drawing direction D) to apply a tensile force to the tough pitch copper foil. At this time, the crosshead speed was set to 2 mm / min, and the distance from directly below the upper fixing jig 11t to just above the lower fixing jig 11b, that is, the effective gauge length G was set to 100 mm.

The characteristics of the tough pitch copper having a tensile strength measured as described above of 300 N / mm ² or more at normal temperature softening were determined as “good”, and less than 300 N / mm ² was determined as “no”.

(Measurement of crystal orientation)
Next, the crystal orientation for improving the bending characteristics of each tough pitch copper foil, that is, the area ratio of the (200) plane which is a cubic structure was measured. Specifically, each tough pitch copper foil was heated in the atmosphere at 180 ° C. for 1 hour, imitating a recrystallization annealing process. Then, the electron backscattering diffraction image showing the crystal orientation of the surface of each tough pitch copper foil was acquired by the electron backscattering diffraction image (EBSP: Electron Back-Scattering Diffraction Pattern) method. This was analyzed and the area ratio of the (200) plane occupied per unit area of the surface of each tough pitch copper foil was calculated | required.

  The allowable value of the area ratio of the (200) plane measured as described above was set to 20% or more.

(Measurement of the number of bendings)
Subsequently, the number of repeated bendings (number of bendings) until each tough pitch copper foil broke was measured, and the bending characteristics were quantitatively evaluated. Specifically, each tough pitch copper foil having a width of 12.5 mm and a length of 250 mm cut out in parallel with the rolling direction was heated at 180 ° C. for 1 hour in the atmosphere, imitating a recrystallization annealing process.

  Subsequently, a bending test was performed using an FPC high-speed bending tester (model: SEK-31C) manufactured by Shin-Etsu Engineering Co., Ltd. FIG. 3 shows a schematic diagram of a general sliding bending test apparatus 20 simulating the FPC high-speed bending tester and the like.

  As shown in FIG. 3, the sample F (tough pitch copper foil) was fixed to the sample fixing plate 21 of the sliding bending test apparatus 20 with screws 22. Next, the sample F was brought into contact with the vibration transmitting unit 23, and the vibration transmitting unit 23 was vibrated in the vertical direction by the oscillation driver 24 to transmit the vibration to the sample F, and the number of bendings until breakage was measured. The measurement conditions were a bending radius R of 1.5 mm, a vibration stroke S of 10 mm, and a vibration speed of 1500 times / minute.

  The allowable value of the number of bendings measured as described above was set to 50,000 times or more. Moreover, the bending characteristic of the tough pitch copper foil that satisfies the above bending number of 50,000 times or more was determined as “good”, and when any one of them was not satisfied, it was determined as “no”.

(3) Evaluation Results of Rolled Copper Foil In Table 1 below, the composition of the tough pitch copper foil according to Examples 1 to 24, Comparative Examples A to C and Comparative Examples 1 to 7 is shown, respectively, and each of the above The measurement results are shown. In the table, numerical values that deviate from the predetermined value are indicated by bold underlining.

As shown in Table 1, the tough pitch copper foils according to Examples 1 to 24 have a specified value T _N calculated based on the concentration of each element contained and the temperature in the hot rolling process, after the final cold rolling process. The thickness and the degree of work in the final cold rolling process all satisfy a predetermined value. Therefore, both the characteristics for softening at room temperature and the bending characteristics were all “good”.

In addition, the tough pitch copper foil according to Comparative Examples A and B does not satisfy a predetermined value in either the thickness after the final cold rolling process or the degree of work in the final cold rolling process, and all the bending characteristics are “No”. It was a judgment. This is probably because the area ratio (%) of the (200) plane was less than 20% and the flexibility could not be exhibited. However, the specified values T _N all satisfy the predetermined value, and all the characteristics against softening at room temperature were “good”. As described above, the property against softening at room temperature and the bending property can be controlled independently.

  In Comparative Example C in which the thickness exceeds the predetermined value, the bending characteristic is “No” even though the area ratio of the (200) plane satisfies the predetermined value. It can be seen that the thickness control is also important for obtaining high bending properties.

Moreover, as for the tough pitch copper foil which concerns on Comparative Examples 1-6, all prescribed value _TN does not satisfy | fill predetermined value, Moreover, about Comparative Examples 4-6, all the work degrees in the last cold rolling process are also predetermined values. Does not meet. Therefore, all the characteristics of Comparative Examples 1 to 6 with respect to softening at room temperature were “No” determinations, and for Comparative Examples 4 to 6, all the bending characteristics were also “No” determinations.

  Moreover, in the tough pitch copper foil which concerns on the comparative example 7, the total density | concentration of another element is 0.031 mass%, and exceeds the predetermined value. For this reason, the characteristic with respect to softening at normal temperature has been judged as “No”.

From the above results, in order to obtain a copper foil containing a predetermined concentration of oxygen (O), sulfur (S), silver (Ag), iron (Fe) and having a flexion number of 50,000 times or more, (200 It is understood that the surface area ratio is 20 or more and the thickness is 5 μm or more and 50 μm or less. As a manufacturing method, in the process in which a hot rolling process is performed at a predetermined temperature, [E] is the concentration (mass%) of the element E contained in the rolled copper foil, and Tr is the temperature (° C.) in the hot rolling process. Then, the specified value T _N defined by T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr may be set to 9.8 or more.

11b Lower Fixing Jig 11t Upper Fixing Jig 20 Sliding Bending Test Device 21 Sample Fixing Plate 22 Screw 23 Vibration Transmitting Unit 24 Oscillation Driver D Pulling Direction F Sample G Effective Gauge Length R Bending Radius S Vibration Stroke

Claims (6)

It is a rolled copper foil used for flexible printed wiring boards,
Contains oxygen (O), sulfur (S), silver (Ag), iron (Fe) at a predetermined concentration,
A hot rolling process is performed at a predetermined temperature,
The specified value T _N defined by the following formula is 9.8 or more,
(200) The area ratio of the surface is 20 or more, and
A rolled copper foil having a thickness of 5 μm or more and 50 μm or less.
T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr
(Here, [E] is the concentration (mass%) of element E contained in the rolled copper foil, and Tr is the temperature (° C.) in the hot rolling step.) The oxygen concentration [O] is 0.0001% by mass or more and 0.1% by mass or less,
The sulfur concentration [S] is 0.0001 mass% or more and 0.01 mass% or less,
The silver concentration [Ag] is 0.0001 mass% or more and 0.01 mass% or less,
The iron concentration [Fe] is 0.0001 mass% or more and 0.003 mass% or less,
The rolled copper foil according to claim 1, wherein a temperature Tr in the hot rolling step is 700 ° C or higher and 1000 ° C or lower. The total concentration of arsenic (As), antimony (Sb), bismuth (Bi), tin (Sn), nickel (Ni), lead (Pb), and silicon (Si) contained is 0.02% by mass or less. The rolled copper foil according to claim 1, wherein the rolled copper foil is provided. The final annealing process has been applied,
4. The rolled copper foil according to any one of claims 1 to 3, wherein a workability after the final annealing step is 80% or more and less than 97%. A method for producing a rolled copper foil used in a flexible printed wiring board,
A hot rolling process in which hot rolling is performed at a predetermined temperature on a copper ingot containing oxygen (O), sulfur (S), silver (Ag), and iron (Fe) at a predetermined concentration; and a final annealing process. Have
Controlling the concentration of each element and the temperature in the hot rolling step, the specified value T _N defined by the following formula is 9.8 or more, and
A method for producing a rolled copper foil, characterized in that the thickness of the rolled copper foil is set to 5 μm or more and 50 μm or less by processing such that the degree of processing after the final annealing step is 80% or more and less than 97%.
T _N = −98 [O] +1840 [S] +2005 [Ag] −824 [Fe] +0.012 Tr
(Here, [E] is the concentration (mass%) of element E contained in the rolled copper foil, and Tr is the temperature (° C.) in the hot rolling step.) It is a rolled copper foil used for flexible printed wiring boards,
Contains oxygen (O), sulfur (S), silver (Ag), iron (Fe) at a predetermined concentration,
The (200) plane area ratio is 20 or more,
The tensile strength is 300 N / mm ² or more, and
A rolled copper foil having a thickness of 5 μm or more and 50 μm or less.

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