JP2006152420A - Electrolytic copper foil and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide electrolytic copper foil whose rough surface has excellent smoothness and bending resistance, and to provide a suitable production method therefor. <P>SOLUTION: As the copper foil, e.g., electrolytic copper foil in which tensile strength after heating at 180°C for 1 hr is ≥50 kgf/mm<SP>2</SP>, elongation percentage after heating at 180°C for 1 hr is ≥3.0%, and surface roughness (Rz) in the rough surface is ≤2 μm is adopted. Further, for the purpose of obtaining the electrolytic copper foil, e.g., a method of producing electrolytic copper foil characterized in that the concentration of gelatine or glue in a copper sulfate based electrolytic solution is 0.67 to 16.7 ppm, the concentration of chlorine ions is 0.2 to 0.5 ppm, the weight ratio between the concentration of gelatine or glue and the concentration of chlorine ions is 1: 0.03 to 0.3, and also, the number average molecular weight of gelatine or glue is 1,000 to 40,000 is adopted. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electrolytic copper foil and a method for producing the same, and more particularly to an electrolytic copper foil having a high tensile strength after heating and a small surface roughness of the rough surface and a method for producing the same.

  Conventionally, copper foil has been widely used as a basic material for producing printed wiring boards used in the fields of electric and electronic industries. Generally, an electrolytic copper foil is bonded to a polymer insulating substrate such as a glass-epoxy substrate, a phenol substrate, and a polyimide by hot press molding to form a copper-clad laminate, and then to form a desired circuit. After the necessary circuits are printed, unnecessary portions are removed by etching, and the elements are soldered to form various printed wiring boards for electro devices. For example, a foldable flexible printed wiring board is a typical example.

  The copper foil used here is a rolled copper foil that has been rolled into a foil shape, and a solution containing copper sulfate as a main component is electrolyzed to deposit copper on the surface of a titanium or stainless steel rotating drum cathode. In addition, there is an electrolytic copper foil produced by continuously peeling this. Among these, electrolytic copper foils have been used for various printed wiring board applications because they are easy to produce continuously as compared with rolled copper foils, and are excellent in production efficiency and price.

  The rolled copper foil and the electrolytic copper foil have different mechanical strength and surface roughness, and have been used properly according to the type of printed wiring board. If the difference is expressed simply, it has been said that there is a difference in surface roughness and bending resistance when compared with electrolytic copper foil and rolled copper foil.

  With regard to the surface roughness of the copper foil, it has been said that the electrolytic copper foil has large irregularities on the rough surface because crystals grow in the thickness direction, and the smoothness of the copper foil is inferior to that of the rolled copper foil. And regarding bending resistance, especially in a flexible printed wiring board, although favorable bending resistance is requested | required, it has been said that electrolytic copper foil is low in bending resistance compared with rolled copper foil.

  As electronic devices become thinner, printed circuit boards with a finer pattern have been demanded, and it is known that the circuit pitch that can be formed mainly depends on the surface roughness of the copper foil, thereby obtaining a fine pattern. For this purpose, the smoothness of the copper foil is essential. In addition, the smoothness of the copper foil is required even in applications requiring flexibility such as a hinge portion of a mobile phone and in high frequency applications. In order to obtain a smooth copper foil, there is a method of mechanically buffing and smoothing the rough surface of the existing copper foil, but curling (a phenomenon in which the copper foil warps) and buffing are generated, The problem of not being able to handle arises. On the other hand, there is a method of smoothing the copper foil by electrolytic polishing. This method causes problems such as dissolution loss and increased processing costs. Therefore, in order to obtain the smoothness of the copper foil, it is most advantageous in cost to select an additive to be added to the electrolytic solution.

  On the other hand, in order to obtain good bending resistance with the electrolytic copper foil, it may be possible to go through a rolling process aiming at high strength by work hardening, but this leads to a significant increase in manufacturing cost. Therefore, in order to give good bending resistance to the electrolytic copper foil, it is desired to directly produce a high-strength electrolytic copper foil with an additive added to the electrolytic solution.

  Conventionally, in order to obtain a smooth electrolytic copper foil or an electrolytic copper foil having good bending resistance, various attempts have been made to achieve it by selecting an additive in the electrolytic solution. The most representative attempt is an attempt to add gelatin or glue or chloride ions to the electrolyte. For example, in the Example of patent document 1 (Unexamined-Japanese-Patent No. 2004-79523), the smoothed electrolytic copper foil is described and it describes that chlorine ion and low molecular weight gelatin are added in electrolyte solution. Patent Document 2 (JP-A-8-296082) discloses a method for producing an electrolytic copper foil excellent in bending resistance using an electrolytic solution containing a certain amount of chloride ions and containing little or no glue. Are listed. Patent Document 3 (Japanese Patent Laid-Open No. 2001-181886) and Patent Document 4 (Patent No. 3270637) also describe a method for producing an electrolytic copper foil in which gelatin and / or glue is contained in an electrolytic solution.

  Patent Document 5 (Japanese Patent Application Laid-Open No. 2004-35918) describes a copolymer of diallyldialkylammonium salt and sulfur dioxide and 3-mercapto-1-sulfonic acid in an electrolytic solution instead of gelatin or glue. It describes a method for producing an electrolytic copper foil having a rough surface with reduced surface roughness and excellent elongation.

JP 2004-79523 A JP-A-8-296082 JP 2001-181886 A Japanese Patent No. 3,270,637 JP 2004-35918 A

  However, the electrolytic copper foils described in Patent Document 1 to Patent Document 5 described above can obtain a certain smoothness and bending resistance, but a flexible printed wiring board (in particular, TAB) in which fine pitches of circuit patterns progress. Products) have been required to have surface smoothness and tensile strength to improve bending resistance.

  In the case of a metal material, if the tensile strength is improved, the material becomes brittle, the toughness is impaired, and the elongation rate is generally lowered. Therefore, in particular, in order to improve the bending resistance, it is necessary to combine the tensile strength and the elongation rate with an appropriate balance.

  As a method to increase the strength of the electrolytic copper foil, which is a metal material, consider one of the following methods: refinement of crystal grains, solid solution strengthening of alloy elements, particle dispersion strengthening using dissimilar metal elements, and work hardening It is common.

  Among these, it seems that the electrolytic copper foil as the alloy copper foil can be most easily realized by using the solid solution strengthening and particle dispersion strengthening theory using different alloy elements. However, it is not preferable that the electrolytic copper foil frequently used for printed wiring boards has an increase in electrical resistance. In particular, when an alloy element that can be strengthened is contained, the electrical resistance of the electrolytic copper foil is likely to increase. In the same way, in the case of electrolytic copper foil, if many additives are added to the electrolytic solution, the additive is contained in the deposited copper and may cause an increase in the electrical resistance of the electrolytic copper foil. I always wanted to reduce the dose.

  In this, it is difficult from the industrial economic theory that the work hardening theory passes the electrolytic copper foil through the rolling process as described above. However, the work hardening theory is that dislocations are introduced into the crystal structure of the metal to increase the dislocation density, and the deformation resistance increases due to the entanglement of the dislocations, thereby increasing the strength of the metal material. Therefore, the crystal structure at the time of electrodeposition of an electrolytic copper foil should just be able to have a moderate strain density with a certain level of dislocations. This theory seems to be a feasible range if new copper electrolysis conditions can be conceived.

  In addition, the refinement of crystal grains means that when the crystal grains in the metal structure are refined, the grain boundary density is increased, the smooth surface where the metal material is deformed is blocked, and the deformation is less likely to occur. . Therefore, in the case of an electrolytic copper foil, it is preferable that the crystal grain size of the crystal structure during electrodeposition is as fine as possible. This theory is also considered feasible if new copper electrolysis conditions can be conceived.

  Therefore, for the purpose of the present invention, a new electrolysis condition is found using an electrolyte solution with a small amount of additive, and it has a good balance of good electrical resistance, good bending resistance, moderate elongation, and good surface roughness. An object of the present invention is to provide an electrolytic copper foil that can be applied not only to a rigid type printed wiring board but also to a flexible printed wiring board.

  As a result of intensive studies, the present inventors have produced an electrolytic copper foil in which the surface roughness of the rough surface of the electrolytic copper foil is set to a predetermined value or less and the tensile strength after high-temperature heating is set to a specific value or more. It was. And this electrolytic copper foil needs to control each density | concentration and density | concentration ratio of gelatin or glue and a chloride ion in the electrolyte solution mentioned later, and to make the number average molecular weight of gelatin or glue into a fixed range. And reached the present invention. These will be described below.

(Electrolytic copper foil)
The electrolytic copper foil according to the present invention has a tensile strength after heating at 180 ° C. × 1 hour of 50 kgf / mm ² or more, an elongation of 3.0% or more after heating at 180 ° C. × 1 hour, and a rough surface roughness ( Rz) is 2 μm or less. Above all, it is characterized by a very high tensile strength after heating.

  Tensile strength after heating is required because the printed wiring board manufacturing process starts with hot pressing, and when necessary, the printed wiring board is distorted and baked. In TAB products, fusing after tin plating There are various heating processes such as heating and heating at the time of solder reflow. Especially in the case of a flexible printed wiring board that is used by bending a product, it is very important whether or not it can withstand repeated bending behavior. In addition, the tensile strength after heating of the electrolytic copper foil is important from the viewpoint of preventing the bending of the inner lead of the TAB product provided with the device hole and preventing the ductile deformation of the inner lead by mounting bonding of the IC chip or the like. Become.

  The bending resistance of the electrolytic copper foil is generally determined by using a test device that can be bent continuously like a pendulum while applying a weight to a strip-shaped (10 mm wide x 15 cm long) electrolytic copper foil sample. Measure the number of folds to break. In this specification, a load of 0.5 kgf, a bending speed of 175 times / min, and a bending radius of 0.8 mm were employed using an MIT folding resistance tester (hereinafter simply referred to as “bending test”).

First, consider the factors that contribute to the bending resistance of electrolytic copper foil. In the case of a metal material, as the tensile strength increases, the elongation rate generally decreases and becomes brittle. Therefore, it is considered that the bending resistance is determined by toughness which is a balance between tensile strength and elongation.
And it is thought that a bending resistance is influenced by the surface state of electrolytic copper foil, especially the condition of the unevenness | corrugation of the surface. It is thought that the electrolytic copper foil as a sample breaks during the bending resistance test due to the propagation of microcracks from the surface of the copper foil that expands and contracts most during bending. If the surface of the electrolytic copper foil has irregularities, Griffith's theory can be applied due to the notch effect of the irregularities, and the microcracks become stress-concentrated portions at the valleys, and microcracks are likely to occur.

  Therefore, in order to improve the bending resistance of the electrolytic copper foil, an appropriate balance between tensile strength and elongation is ensured, and the surface roughness is made as smooth as possible to reduce the origin of microcracks. It is thought that it needs to be reduced.

  From the above, the present inventors have used an electrolytic copper foil in consideration of an appropriate balance of the three factors of tensile strength, elongation rate, and surface roughness. Hereinafter, each characteristic will be described.

Tensile strength: As for the tensile strength of general electrolytic copper foil, the normal tensile strength is 35 kgf / mm ^{2 to} 52 kgf / mm ² , and the tensile strength after heating at 180 ° C. × 1 hour is 28 kgf / mm ² to Softens to a level of 48 kgf / mm ² . However, in the case of the electrolytic copper foil according to the present invention, the tensile strength after heating at 180 ° C. for 1 hour is 50 kgf / mm ² or more. Conventionally, there has been no electrolytic copper foil having such a high tensile strength after heating.

Then, it is more preferable that the tensile strength after heating this 180 ° C. × 1 hour in the range of ^{50kgf / mm 2 ~55kgf / mm 2} . When the tensile strength after heating at 180 ° C. for 1 hour is less than 50 kgf / mm ² , it is clear that the softening after heating is remarkable, and wrinkles during handling are easily generated, which is required for a flexible printed wiring board. Bending resistance cannot be obtained. On the other hand, when the tensile strength after heating at 180 ° C. for 1 hour exceeds 55 kgf / mm ² , the tendency to embrittle becomes prominent, and the tendency for the elongation to become less than 3.0% increases. As the toughness of the electrolytic copper foil, It cannot be said that it is good. The reason why the condition of 180 ° C. × 1 hour is adopted as the heating condition is that the heat treatment condition close to the press forming temperature of a normal rigid substrate is adopted.

Furthermore, as one of the characteristics of the electrolytic copper foil according to the present invention, the tensile strength in the normal state before heating is very high, and the normal tensile strength usually exceeds 60 kgf / mm ² . However, according to the studies by the present inventors, the normal tensile strength of the electrolytic copper foil according to the present invention seems to be experimentally in the range of 58 kgf / mm ^{2 to} 65 kgf / mm ² .

Elongation rate: The elongation rate should be 3.0% or more after heating at 180 ° C. for 1 hour. In order to ensure good toughness as described above, a balance between the elongation and the tensile strength is important. When the elongation percentage is less than 3.0%, even if the tensile strength of the electrolytic copper foil after heating at 180 ° C. for 1 hour exceeds 50 kgf / mm ² , it is simply embrittled and has good toughness (= flexi Therefore, the bending resistance is not improved. On the other hand, the upper limit is not specified, but it is about 4.5%. When the elongation percentage after heating at 180 ° C. for 1 hour exceeds 4.5%, the tensile strength is lowered, it becomes impossible to maintain good toughness, and the bending resistance deteriorates. Further, the normal elongation is preferably 3.5% to 5.0%. As a feature of the electrolytic copper foil according to the present invention obtained by the manufacturing method described later, the elongation before and after heating does not change greatly, but the elongation after heating tends to slightly decrease compared to the normal elongation.

Surface roughness: The electrolytic copper foil is made by flowing a copper sulfate-based solution between a drum-shaped rotating cathode and a lead-based anode or the like arranged along the shape of the rotating cathode, and using an electrolytic reaction. Copper is deposited on the drum surface of the rotating cathode, and the deposited copper becomes a foil, which is continuously peeled off from the rotating cathode and wound up.

  The surface of the electrolytic copper foil that has been peeled off from the state in contact with the rotating cathode is a transfer of the mirror-finished surface shape of the rotating cathode, and is called a glossy surface because it is glossy and smooth. On the other hand, the surface shape of the electrolytic copper foil that was the precipitation side shows a mountain-shaped uneven shape because the crystal growth rate of the deposited copper differs for each crystal plane, and this is called a rough surface.

  As can be seen from the above description, the surface roughness of the glossy surface is determined by the degree of mirror finish on the surface of the rotating cathode. On the other hand, the surface roughness of the rough surface greatly depends on electrolysis conditions such as the electrolytic solution, current density, and solution temperature. The surface roughness (Rz) of the rough surface referred to in the present invention is as close as possible to the roughness of the glossy surface and is 2 μm or less. When the surface roughness of the rough surface exceeds 2 μm, even if the tensile strength and the elongation rate are within the above-mentioned appropriate ranges, the bending resistance is not improved and the copper foil for forming a fine pitch pattern is suitable. It will be lacking. More preferably, the surface roughness (Rz) of the rough surface is 0.7 μm to 1.5 μm. When the surface roughness of the rough surface is 1.5 μm or less, the bending resistance can be stably improved. The lower limit is specified as 0.7 μm, which is a production limit value obtained by the production method described later.

Thickness of electrolytic copper foil: The above-described tensile strength and elongation rate are not inherently dependent on the thickness. However, the surface roughness of the rough surface generally depends on the thickness of the electrolytic copper foil, and the roughness increases as the thickness increases. Therefore, in the present invention, it is clarified that the electrolytic copper foil of 7 μm to 20 μm is mainly targeted.

(Method for producing electrolytic copper foil)
The production of the electrolytic copper foil is “a method of producing an electrolytic copper foil having a tensile strength after heating at 180 ° C. × 1 hour of 50 kgf / mm ² or more, wherein the gelatin or glue concentration in the copper sulfate electrolyte is 0. .67 ppm to 16.7 ppm, chloride ion concentration is 0.2 ppm to 0.5 ppm, weight ratio of gelatin or glue concentration to chloride ion concentration is 1: 0.03 to 0.3, and number average of gelatin or glue The manufacturing method of the electrolytic copper foil characterized by having a molecular weight of 1000-40000 is adopted.

  Moreover, in manufacture of the electrolytic copper foil which concerns on this invention, the manufacturing method of the said electrolytic copper foil whose density | concentration of the said gelatin or glue is 1 ppm-15 ppm is provided.

  Moreover, in manufacture of the electrolytic copper foil which concerns on this invention, the manufacturing method of the said electrolytic copper foil whose said chlorine ion concentration is 0.3 ppm-0.5 ppm is provided.

  Moreover, in manufacture of the electrolytic copper foil which concerns on this invention, the weight ratio of the said gelatin or glue density | concentration and chloride ion concentration provides the manufacturing method of the said electrolytic copper foil which is 1: 0.03-0.2. is there.

  Moreover, in manufacture of the electrolytic copper foil which concerns on this invention, the manufacturing method of the said electrolytic copper foil whose number average molecular weights of the said gelatin or glue are 1500-20000 is provided.

  According to the electrolytic copper foil of the present invention, since the surface roughness of the rough surface is small and smooth, it is possible to form a fine pitch pattern, and it has smoothness and tensile strength after high-temperature heating. Is at a high level, and has an appropriate balance with the elongation after heating, and therefore is extremely excellent in the bending resistance required for the flexible printed wiring board. Moreover, the manufacturing method of the present invention enables the electrolytic copper foil to be efficiently produced on an industrial scale.

(Production form of electrolytic copper foil according to the present invention)
The method for producing an electrolytic copper foil according to the present invention contains gelatin or glue and chloride ions in a certain concentration in a copper sulfate electrolyte, and after heating at 180 ° C. for 1 hour (hereinafter also referred to as high-temperature heating). An electrolytic copper foil having a tensile strength of 50 kgf / mm ² or more, an elongation of 3.0% or more after heating at 180 ° C. for 1 hour, and a rough surface having a surface roughness (Rz) of 2 μm or less is obtained.

As the electrolytic solution, an acidic copper sulfate solution is used. In general, a composition composed of 200 g / l to 600 g / l of copper sulfate pentahydrate and 20 g / l to 200 g / l of free sulfuric acid is used as a basic bath composition. The electrolysis conditions are a bath temperature of 20 ° C. to 70 ° C., a current density of 50 A / dm ^{2 to} 150 A / dm ² , and an electrolysis time of 10 seconds to 300 seconds.

  The electrolytic solution contains gelatin or glue. The gelatin or glue concentration is preferably 0.67 ppm to 16.7 ppm, more preferably 1 ppm to 15 ppm in view of stable productivity and yield on an industrial scale. If the gelatin or glue concentration is out of the above range, a good balance between high tensile strength and elongation after high-temperature heating cannot be obtained, or the surface roughness (Rz) of the rough surface becomes large.

  The number average molecular weight of gelatin or glue used at this time is preferably in the range of 1000 to 40000. Furthermore, the use of those having a number average molecular weight in the range of 1500 to 20000 properly maintains the three elements of tensile strength after heating, elongation rate, and surface roughness of the rough surface, and produces high yield. Is preferable. When the number average molecular weight of gelatin or glue is out of the above range, an appropriate balance between high tensile strength and elongation after high-temperature heating cannot be obtained, or the surface roughness (Rz) of the rough surface increases.

  Here, a method for measuring the number average molecular weight of the gelatin or glue will be described. The number average molecular weight referred to in the present invention is measured using a gel permeation chromatography (GPC) method of a sample solution having a concentration of 3 ppm to 5 ppm in which the above organic substance is dissolved in water. In the present invention, a mixed solution of 20% by volume of acetonitrile and 80% by volume of dilute sulfuric acid having a concentration of 5 mM is used as the mobile phase, this mobile phase is sent out by a liquid feed pump, 200 μl of the sample solution is injected into this, and then arranged in series. Three columns were passed. The first column is a PEEK column having an inner diameter of 7.5 mm and a length of 250 mm, containing a Sephadex G-15 (exclusion limit molecular weight 1500) particle size 66 μm or less filler made by Amsham Pharmacia Biotech. The second and third columns are Asahipak GS-320HQ (exclusion limit molecular weight 40000) manufactured by Showa Denko KK, an inner diameter of 7.6 mm, and a length of 300 mm. The molecular weight distribution of gelatin or glue was measured using an absorbance detector (UV210 nm) after passing through the first column to the third column, and the number average molecular weight was calculated.

In the measurement of the number average molecular weight of gelatin or glue, the reagents used for preparing a calibration curve are as follows. The concentration of gelatin or glue was measured by preparing a calibration curve using an aqueous solution of known gelatin or glue concentration.
(reagent)
・ ALBUMIN, BOVINE SERUM (Sigma Aldrich Japan Co., Ltd., molecular weight 66000)
CYTOCHROME C (Sigma Aldrich Japan Co., Ltd., molecular weight 12400)
・ APROTININ (Sigma Aldrich Japan Co., Ltd., molecular weight 6500)
INSULIN (Sigma Aldrich Japan Co., Ltd., molecular weight 5734)
INSULIN CHAIN B, OXIDIZED (Sigma Aldrich Japan Co., Ltd., molecular weight 3496)
・ NEUROTENSIN (manufactured by Sigma Aldrich Japan Co., Ltd., molecular weight 1673)
・ ANGIOTENSIN II (Sigma Aldrich Japan Co., Ltd., molecular weight 1046)
VAL-GLU-GLU-ALA-GLU (Sigma Aldrich Japan, molecular weight 576)

  The electrolytic solution contains chlorine ions. The chlorine ion concentration is preferably 0.2 ppm to 0.5 ppm, more preferably 0.3 ppm to 0.5 ppm from the viewpoint of producing with good yield. If the chlorine ion concentration is outside the above range, the three elements of tensile strength after heating, elongation rate, and surface roughness of the rough surface are likely to vary, and in particular, the surface roughness (Rz) of the rough surface tends to increase. It is in.

  As can be understood from the above, the blending ratio of gelatin or glue concentration and chloride ion concentration in the above electrolyte is a weight ratio ([gelatin or glue concentration in electrolyte]: [chloride ion concentration]). Is from 1: 0.03 to 0.3, and from the viewpoint of being particularly excellent in production stability, it is more preferably from 1: 0.03 to 0.2. If the weight ratio between the gelatin or glue concentration and the chloride ion concentration is out of the above range, an appropriate balance among the three factors of tensile strength after heating, elongation rate, and surface roughness of the rough surface cannot be maintained.

  By performing electrolysis using the above electrolytic solution, electrolytic copper foil electrodeposited on a drum-type cathode and continuously produced has three elements: tensile strength after heating, elongation rate, and surface roughness of the rough surface. Is maintained, and the bending resistance after high-temperature heating is dramatically improved. Hereinafter, the present invention will be described more specifically based on examples.

A sulfuric acid copper solution of CuSO ₄ · 5H ₂ O (Cu 80 g / l) and H ₂ SO ₄ (140 g / l) contains glue (2 ppm) and chlorine ions (0.3 ppm) having a number average molecular weight of 1570 ( A copper foil was electrodeposited on a titanium cathode under the electrolytic conditions of glue / chlorine weight ratio 1: 0.15), bath temperature 50 ° C., and current density 60 A / dm ² , and peeled and collected.

  The thickness of this electrolytic copper foil was 18 μm, and the tensile strength, elongation, bending resistance, and surface roughness of the rough surface after normal and high temperature heating were measured. The tensile strength and elongation (normal state and after high temperature heating) were measured according to IPC-TM-650, and surface roughness (Ra = arithmetic average roughness, Rz = 10-point average roughness, Ry = maximum) The roughness was measured with a surface roughness meter (stylus tip radius of curvature 0.2 μm) in accordance with JIS B 0601 (1994). The results are shown in Table 1 together with other examples and comparative examples as Example 1.

CuSO ₄ · 5H ₂ O (Cu 80 g / l), H ₂ SO ₄ (140 g / l) in sulfuric acid copper solution containing glue (10 ppm) and chlorine ions (0.5 ppm) with a number average molecular weight of 20,000 ( The weight ratio of glue and chlorine was 1: 0.05), the copper foil was electrodeposited on the titanium cathode under the electrolytic conditions of bath temperature 50 ° C. and current density 60 A / dm ² , and peeled and collected.

  The thickness of this electrolytic copper foil was 18 μm, and in the same manner as in Example 1, the tensile strength, elongation rate, bending resistance, and surface roughness of the rough surface after normal and high-temperature heating were measured. The results are shown in Table 1 together with other examples and comparative examples as Example 2.

Comparative example

(Comparative Example 1)
In this comparative example, among the commercially available electrolytic copper foils, an electrolytic copper foil having a high tensile strength and a roughened surface with a low roughness was produced. CuSO ₄ · 5H ₂ O (Cu: 80 g / l), H ₂ SO ₄ (140 g / l) in sulfuric acid copper solution, number average molecular weight 5500 glue (1.8 ppm) and chloride ion (1.5 ppm) Copper foil was electrodeposited on a titanium cathode under electrolytic conditions of a bath temperature of 50 ° C. and a current density of 60 A / dm ² .

  The thickness of this electrolytic copper foil was 18 μm, and the tensile strength, elongation, bending resistance, and surface roughness of the rough surface after normal and high temperature heating were measured. The results are shown in Table 1 together with other examples and comparative examples as Comparative Example 1.

(Comparative Example 2)
In this comparative example, a commercially available electrolytic copper foil having an elongation after heating of 3% or more was produced. CuSO ₄ · 5H ₂ O (Cu: 80 g / l), H ₂ SO ₄ (140 g / l) in an acidic copper sulfate solution containing glue (1 ppm) and chlorine ions (15 ppm) with a number average molecular weight of 20,000 (glue) And a weight ratio of chlorine of 1:15), a copper foil was electrodeposited on a titanium cathode under the electrolytic conditions of a bath temperature of 50 ° C. and a current density of 60 A / dm ² , and stripped and collected.

  The thickness of this electrolytic copper foil was 18 μm, and the tensile strength, elongation, bending resistance, and surface roughness of the rough surface after normal and high temperature heating were measured. The results are shown in Table 1 together with other examples and comparative examples as Comparative Example 2.

(Comparative Example 3)
In this comparative example, recrystallization occurred by heating near 180 ° C., an annealing effect was obtained, and an electrolytic copper foil having a high elongation after heating was produced. CuSO ₄ .5H ₂ O (Cu: 80 g / l), H ₂ SO ₄ (140 g / l), 15 ppm chlorine concentration sulfuric acid copper solution is subjected to activated carbon filtration, electrolysis with a bath temperature of 50 ° C. and a current density of 60 A / dm ² Under the conditions, a copper foil was electrodeposited on a titanium cathode and peeled and collected.

  The thickness of this electrolytic copper foil was 18 μm, and the tensile strength, elongation, bending resistance, and surface roughness of the rough surface after normal and high temperature heating were measured. The results are shown in Table 1 together with other examples and comparative examples as Comparative Example 3.

<Contrast between Example and Comparative Example>
As can be seen from Table 1, the results of the bending resistance test are much higher than those of the comparative examples, both in the normal state and after heating of the electrolytic copper foils obtained in Example 1 and Example 2 above. I understand. When comparing with other characteristics, it can be seen that the tensile strength is high especially in the normal state and after heating. On the other hand, both the normal state and the post-heating elongation rate of the electrolytic copper foil obtained in Example 1 and Example 2 are inferior in terms of value rather than the elongation rate of each comparative example. In particular, although the elongation percentage after heating of Comparative Example 3 is high, the tensile strength after heating is low, and it cannot be said that the folding resistance is good. Therefore, from the viewpoint of such physical properties, it is supported that there is an appropriate balance between tensile strength and elongation rate in order to improve the bending resistance.

  Moreover, when the roughness of a rough surface is seen, the electrolytic copper foil obtained in the said Example 1 and Example 2 has shown the value lower than any electrolytic copper foil of each comparative example. Therefore, in order to improve the bending resistance performance in the present invention, it is considered that notches due to unevenness that become the starting point of occurrence of microcracks during bending can be greatly reduced.

  The electrolytic copper foil according to the present invention has a high tensile strength after high-temperature heating, and has an appropriate balance between the tensile strength and the tensile strength after high-temperature heating, and the surface roughness (Rz) of the rough surface is small. Therefore, it shows extremely high bending resistance. Also, it is suitable for manufacturing high density printed wiring boards, especially flexible wiring boards and TAB tape carriers that require high bending resistance, since the surface roughness of the rough surface is small and fine pitch circuits can be easily formed. It is done. In addition, the production method of the present invention enables efficient production of the electrolytic copper foil on an industrial scale.

Claims (9)

The tensile strength after heating at 180 ° C. for 1 hour is 50 kgf / mm ² or more, the elongation is 3.0% or more after heating at 180 ° C. for 1 hour, and the surface roughness (Rz) of the rough surface is 2 μm or less. Electrolytic copper foil characterized by. Electrolytic copper foil according to claim 1 tensile strength after heating above 180 ° C. × 1 hour is ^{50kgf / mm 2 ~55kgf / mm 2} . The electrolytic copper foil according to claim 1 or 2, wherein a surface roughness (Rz) of the rough surface is 0.7 µm to 1.5 µm. The electrolytic copper foil according to any one of claims 1 to 3, wherein a tensile strength in a normal state is 60 kgf / mm ² or more. A method for producing an electrolytic copper foil having a tensile strength of 50 kgf / mm ² or more after heating at 180 ° C. for 1 hour,
The gelatin or glue concentration in the copper sulfate electrolyte is 0.67 ppm to 16.7 ppm, the chloride ion concentration is 0.2 ppm to 0.5 ppm, and the weight ratio of the gelatin or glue concentration to the chloride ion concentration is 1: 0.03. A method for producing an electrolytic copper foil, wherein the number average molecular weight of gelatin or glue is 1000 to 40000. The method for producing an electrolytic copper foil according to claim 5, wherein the concentration of the gelatin or glue is 1 ppm to 15 ppm. The said copper ion concentration is 0.3 ppm-0.5 ppm, The manufacturing method of the electrolytic copper foil of Claim 5 or Claim 6. The method for producing an electrolytic copper foil according to any one of claims 5 to 7, wherein a weight ratio of the gelatin or glue concentration to the chloride ion concentration is 1: 0.03 to 0.2. The method for producing an electrolytic copper foil according to any one of claims 5 to 8, wherein the gelatin or glue concentration has a number average molecular weight of 1500 to 20000.