TW574441B - Electrolytic copper foil for copper-clad laminate, and manufacturing method thereof - Google Patents

Description

A7 574441 ___ Β7_ V. Description of the Invention (1) [Technical Field] The present invention relates to an electrolytic copper foil for a copper area laminate that can precisely form a fine-pitch wiring pattern and a method for manufacturing the same. [Background Art] As copper foil for copper area laminates used in printed wiring (circuit) boards, electrolytic copper foil is often used. Generally, "this electrolytic copper foil is produced by electrodeposition of copper on a rotating drum, and then the copper precipitates deposited on the drum are peeled off to be continuously manufactured, but the surface of the peeled copper foil" that is in contact with the drum becomes The flat glossy surface (S surface), and the opposite surface (electrolyte side) becomes the rough surface (M surface). In addition, the rough surface usually has a large number of irregularities with large fluctuations. This electrolytic copper foil precipitates out of the structure at the initial stage on the tube. The crystal grain diameter is small and the direction is irregular, but as the precipitation progresses, the crystal structure becomes directional along the precipitation direction, and the crystal grain size also becomes coarse. In addition, the conventional electrolytic copper foil uses such rough surface irregularities to obtain the bonding strength with the resin substrate. To further improve the bonding strength, it is necessary to roughen the fine particles to which copper can be attached. When this electrolytic copper foil is used for a copper area laminate, usually one side or both sides of a glass or epoxy substrate is used, so that the rough side of the aforementioned electrolytic copper foil faces the resin substrate, and is thermocompression bonded or It is used by thermocompression bonding through an adhesive. The copper foil of the obtained copper area laminate is etched to form a wiring pattern. In recent years, fine-pitch wiring patterns have been required to be formed on copper area laminates. In the case of forming such a fine-pitch wiring pattern by etching, 3 paper sizes apply the Chinese National Standard (CNS) A4 specification (210 X 297 public love) '(Please read the precautions on the back before filling this page)

574441 A7 ___B7___ V. Description of the Invention (V) Using the copper area laminates of the conventional electrolytic copper box, the etched wiring pattern cross-section is as shown in Figure 1. Etching has occurred to make the upper bottom 1 narrow and the lower bottom 2 wide. Ladder-shaped phenomenon. In FIG. 1, reference numeral 3 denotes a copper foil, and reference numeral 4 denotes a resin substrate. In order to prevent a short circuit of the ladder-shaped conductive pattern, the interval must be wider, so there is a problem that a fine pattern cannot be formed. Originally, it is desirable that the upper base 5 and the lower base 6 are aligned substantially vertically as a whole, as shown in FIG. The trapezoidal wiring pattern described above cannot form a fine-pitch wiring pattern due to the undercut difference. If the cause of this poor etching is further investigated, it is the rough surface of the electrolytic copper foil. When the unevenness of the rough surface becomes more prominent, the lower part of the pattern portion remaining during etching will be widened, so it is on the upper side compared to the resin substrate The part is subject to a greater degree of etching. When expressed in terms of an etching factor, the following results are obtained. That is, as shown in FIG. 3, regarding the thickness a of the copper foil and the width b of the portion where the lower width is over-etched, the larger the a / b (etching factor), the better the etching performance of the fine-pitch wiring pattern. . However, the above-mentioned unevenness of the rough surface of the conventional electrolytic copper foil is inevitable formed in the manufacturing process, and based on the consideration of improving the bonding strength with the resin substrate, this method is also recommended. Therefore, conventionally, there has been no idea of reducing the unevenness of the rough surface of the copper foil or making it finer in the electrolytic copper foil manufacturing process. However, based on the above requirements for forming fine-pitch wiring patterns on the copper area laminates, the degree of unevenness must be shown in the process of electrolytic copper foil. 4 This paper is appropriate.] Chinese National Standard (CNS) A4 Specification (21G X (297 meals) (Please read the notes on the back before filling out this page)

574441 A7 ____B7__ 5. Description of the invention (h) Improvement of rough surface. [Disclosure of the Invention] The present invention has been made in view of the above problems, and an object thereof is to provide an electrolytic copper foil for a copper area laminate, in which a fine-pitch wiring pattern is formed by etching a copper area laminate using the electrolytic copper foil, It can prevent the upper bottom from being significantly etched compared to the resin substrate side due to the lower bottom being widened during etching. As a result, the cross-sectional shape of the wiring pattern shows a trapezoidal shape with a narrow upper bottom and a wide bottom bottom. Roughly vertical etched surface. In order to achieve the above object, the present invention provides: 1 An electrolytic copper foil for copper area laminates, which uses electrolytic copper foil; characterized in that the surface roughness RZ of the rough surface of the electrolytic copper foil is 1.5 ~ 4.0 / / m; 2 The electrolytic copper foil for copper area laminates according to 1 above, wherein the surface roughness Rz of the rough surface of the electrolytic copper foil is 1.5 to 2.5 / zm; 3 The electrolytic for copper area laminates according to 1 or 2 above Copper foil, wherein the rough surface of the aforementioned electrolytic copper foil is an electrolytic honing surface or a chemical honing surface; 4. The electrolytic copper foil for copper area laminates according to the above 3 items is one using electrolytic copper foil, of which, The rough surface of the electrolytic copper foil is subjected to electrolytic honing or chemical honing, and then the electrolytic honing or chemical honing is further subjected to a roughening treatment so that the roughness Rz of the roughened surface becomes 1.5 to 4.0. // m; 5 The electrolytic copper foil for copper area laminates according to the above 4, wherein the roughness Rz of the roughened surface is 1.5 to 2.5 // m; 6 For the copper area laminates according to 4 or 5 above Electrolytic copper foil, of which 5 paper sizes are applicable to China National Standard (CNS) A4 (210 X 297 mm) (please Read the notes on the back and fill in this page) ϋ nn ϋ n One-by-one, II ϋ n ϋ n II · _1 nn I ϋ n II ϋ nn ϋ ϋ I ϋ n ϋ nn -ϋ 1 574441 A7 B7 V. Description of the invention (The particle size of this chemical treatment is below 1.5 / zm; 7—A kind of manufacturing method of electrolytic copper foil for copper area laminates' is to roughen the electrolytic copper foil by electrolytic honing or chemical honing to make the electrolytic copper box The surface roughness Rz of the rough surface is 1.5 to 4.0 // m; 8 As described in the above 7 method of manufacturing the electrolytic copper foil for copper area laminates, the rough surface of the electrolytic copper foil is electrolytically honing or chemically honing. The surface roughness Rz of the rough surface of the electrolytic copper foil is 1.5 to 9; 9 The manufacturing method of the electrolytic copper foil for the copper area laminate of the above 8 is the electrolytic honing or chemical honing of the rough surface of the electrolytic copper foil 'Then proceed to roughen the electrolytic honing surface or the chemical honing surface' so that the roughness Rz of the roughened surface is 1.5 to 4.0 // m; 10 The electrolysis of the copper area laminate according to 9 above The manufacturing method of the copper foil is to set the roughness Rz of the roughened surface to 1.5 to 2.5 // m; 11 as above The method of manufacturing electrolytic copper foil for copper area laminates of 9 or 10, wherein the size of the roughened particles is the following; 12 As described above for the method of manufacturing electrolytic copper foil for copper area laminates of 9 to 11, the use of chloride Sulfuric acid acidic sulfuric acid solution with ion concentration below 2mg / l to produce electrolytic copper foil. [Simplified description of the figure] Figure 1 is a cross-sectional illustration of a wiring pattern formed by etching a copper area laminate of a conventional electrolytic copper foil FIG. 2 is a cross-sectional explanatory diagram of a wiring pattern formed by etching of an ideal copper area laminate. FIG. 3 is a schematic explanatory diagram of an etching factor. 6 This paper size is in accordance with Chinese National Standard (CNS) A4 (210 X 297 mm). 靖 Jing first read the > I matter on the back and then fill out this page) IAW -------- ^ Order --- ----_ Line I Thai 574441 A7 __B7___ 5. Explanation of the invention (<) [Embodiments of the invention] The electrolytic copper foil is electrodeposited with copper on a rotating drum, and then the copper deposited on the drum is precipitated. However, as described above, the side that is in contact with the cylinder becomes a flat glossy surface, and the opposite side (the electrolyte side) becomes a rough surface with significant unevenness, as described above. The structure of this electrolytic copper foil at the initial stage of precipitation has a small crystal grain size and an irregular direction. However, as the precipitation progresses, the crystal structure will have directivity along the precipitation direction, and the crystal grain size tends to increase. In the present invention, based on the insight that the crystalline structure formed by the above-mentioned electrolysis must be improved, the rough surface of the electrolytic copper box with significant unevenness as described above is electrolytically polished or chemically polished in the electrolytic copper foil manufacturing process. Grinding, so that the surface roughness Rz of the rough surface of the electrolytic copper foil becomes 1.5 to 4.0 // m ° After roughening the rough surface of the electrolytic copper foil by electrolytic honing or chemical honing, further roughening the honing surface, It is desirable that the roughness Rz of the roughened surface be 1.5 / zm to 4.0 / zm. Thereby, not only a good etching factor can be obtained, but also peeling strength can be improved. At this time, the size of the roughened particles after electrolytic honing or chemical honing is preferably 1.5 / zm or less. If Rz exceeds 4.0 // m, the effect of the present invention (that is, the effect of forming a fine-pitch wiring pattern with high accuracy during the etching of a copper area laminate) cannot be obtained sufficiently, and when Rz is less than 1.5 / / m, the bonding strength with the resin substrate will be low, so Rz is set to 1.5 / zm or more. Better 7 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm) (Please read the notes on the back before filling this page) -IAV -------- ^ ________ I IAV- --I ------------------ 574441 A7 ___B7__ 5. Description of the invention (b) The situation is to set the surface roughness of the rough surface or roughened surface of the electrolytic copper foil 1.5 ~ 2.5 // m. This can alleviate the significant unevenness of the rough surface inevitably formed in the conventional electrolytic copper foil manufacturing process, and can effectively prevent the formation of wiring patterns when etching the copper area laminates using electrolytic copper foil. An etching phenomenon of a trapezoidal shape with a narrow upper bottom and a wide lower bottom appears, and an approximately vertical etching surface can be obtained. When honing the rough surface of the electrolytic copper foil, for example, an electrolytic honing process can be set in continuous and plural electrochemical surface treatments such as roughening the surface of the electrolytic copper foil, and copper is disposed in the electrolytic solution of the process. In contrast to a cathode plate (directly connected to an electrode) for collecting electricity from a copper foil, the foil is electrolytically honed by a liquid-collecting method. This makes it possible to effectively perform continuous honing of the copper foil. As described above, the present invention aims to reduce the surface roughness of the rough surface of the electrolytic copper foil, but it is also possible to use various types of roughening treatment of the rough surface of the electrolytic copper foil or various kinds of glossy surfaces as necessary. For electrochemical surface treatment, the present invention also includes these treatment methods. The same effect can be obtained even if the chemical honing is performed instead of the electrolytic honing. An example of electrolytic honing is shown below. (Honing fluid) H3P〇3: 70vol% Water: 30vol〇 / 〇 (Honing conditions) '8 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm). Read the notes on the back and fill in this page) IAW -------- Order --------- line · 574441 A7 ______ B7 _ 5. Description of the invention (,))

Current density (Dk): 10 ~ 20A / dm2 Time: 30 ~ 60 seconds Voltage: 3V In addition, the roughening treatment on the surface that has been electrolytically or chemically honed can be performed in the past (for example, Japan) (Patent No. 1927340) Subtle roughening treatment. Specific examples of the roughening treatment include Cu-Co-Ni ternary alloy plating described below. However, the roughening treatment of the present invention may use treatments other than the above, as long as it is suitable for the conditions of the present invention, there is no particular limitation. (Plating bath composition and plating conditions)

Cu: 10 ~ 20g / l

Co: 1 ~ 10g / l

Ni ·· 1 to 10 g / l pH: 1 to 4

Temperature: 40 ~ 50 ° C, Current density Dk: 20 ~ 30A / dm2, Time: 1 ~ 5 seconds, or 'The present invention can be used in addition to the above-mentioned electrolytic honing of electrolytic copper foil. It can be used: set by chloride ion concentration The technology of making electrolytic copper foil with acidic copper sulfate solution of sulfuric acid below 2mg / l will get the effect of one layer. By limiting the chloride ion concentration, the crystalline structure of the electrolytic copper foil becomes fine, and crystals will not grow in a specific direction, and a knot with less unevenness can be obtained. 9 This paper is compliant with China National Standard (CNS) A4 specifications (21 〇X 297mm) One " " (Please read the notes on the back before filling this page)

I-· 11111111 I — — — — — — — — — — — I — — — — — I I I I I 574441 A7 ____B7___ 5. Description of the invention (S) structure. Thereby, the amount of electrolytic honing can be appropriately adjusted, the etching can be prevented from becoming a trapezoidal shape with a narrow top and a bottom, and a fine-pitch wiring pattern can be effectively formed. If the chloride ion concentration at this time exceeds 2 mg / l, the effect of limiting the chloride ion concentration can hardly be expected. Therefore, the chloride ion concentration must be below 2 mg / l. A preferred chloride ion concentration is 0.5 mgn. In addition, the amount of the glue usually used in the production of copper foil is set to 0.5 mg / l or less, and preferably (). 2 mg A or less. In order to suppress the crystalline growth in the specific direction, an electrolytic copper foil with less unevenness is obtained. The effect is even more significant. If the amount of gum added exceeds 0.5 mg / l, the effect of adding the gum can hardly be expected. Therefore, it must be 0.5 mg / l or less. The copper foil obtained by the electrolytic copper box manufacturing process in which the chloride ion concentration and the amount of the glue is reduced as described above is excellent in bending resistance and good in recrystallization after heat treatment. This is a confirmable effect. The following shows an example of a preferable electrolyte composition and electrolytic conditions in the electrolytic copper foil manufacturing process. (Composition of electrolyte)

Copper sulfate (CuS04 · 5H20): 200 ~ 600ge Sulfuric acid (H2S04): 20 ~ 200gA Chloride ion (Cl_): 2 mg / l or less, preferably 0.5 mg / l or less Gel: Do not add. If it is added, it is less than 0.5mg / l (preferably less than 0.2mg / l). 10 This paper size is applicable to China National Standard (CNS) A4 (210 X 297 mm). (Please read the precautions on the back before (Fill this page). · A — — — — — — — — — — — — — — — — — — — — — — — — 574441 A7 ___B7 ___ V. Description of the Invention (Gas) (Electrolysis Conditions) Electrolyte temperature: 20 ~ 70 ° C Current density: 50 ~ 200A / dm2 Electrolysis time: 10 ~ 300 seconds Anode: Lead (Pb) Examples Next, it will be explained based on the examples. This embodiment is only an appropriate example, and the present invention is not limited to this embodiment. Therefore, the modifications, other embodiments, and aspects included in the technical idea of the present invention are all included in the present invention. (Example 1) An electrolytic copper foil having a thickness of 18 to 12 // m was continuously produced using a cylindrical cathode. The composition of the electrolytic solution is copper sulfate (CuS04 · 5H20): 500g / l, sulfuric acid (H2S04): 100g / l, chloride ion (C0: 0.45mg / l, gum: 0.5mgy ^ l), and the temperature of the electrolyte: Electrolysis at 60 ° C, current density: 100A / dm2. The surface roughness RZ of the rough surface of the electrolytic copper foil obtained was 4 · 4 ~ 4.8 / zm. The surface roughness of the glossy surface was u. This sample is further divided into five, and as a honing fluid, H3P03: 70vol%, water: 30vol%, and the honing conditions are set at a current density of 10 to 20A / dm2, and a time of 30 to 60 seconds, Voltage: The range of 3V is changed. For the aforementioned five samples, the electrolytic honing of the rough surface of the electrolytic copper foil is performed, and the above-mentioned fine roughening treatment is further applied to the treated surfaces, so that 11 paper sizes are suitable for China S. Home Standard (CNS) A4 Specification (210 X 297 Male One One) (Please read the precautions on the back before filling this page) · -------- Order 丨 Line 丨-574441 A7 _____B7 ______ V. Invention Explanation ("0") The final surface roughness of the rough surface becomes Rz4.0 // m, Rd.S / zm, Rz2.5 // m, Rz2.0 // m, Rzl.5 // m, which are referred to as sample 1, sample 2, sample 3, sample 4, sample 5 〇 press the rough surface side of the electrolytic copper foil obtained above the sample 1, sample 2, sample 3, sample 4, and sample 5 Next, each copper area laminate was made on one side of the glass epoxy substrate. Dry laminate films were further laminated on the copper area laminate, and then a pattern film with a photoresistance width of 100 # m and a circuit interval of 100 # m was exposed to UV. A circuit pattern is made. Next, it is etched with a copper chloride etchant. As a result, the lengths of the upper and lower bottoms of the obtained wiring pattern are shown in Table 1. Similarly, the etching factor (a / b) is also It is shown in the same table. In addition, these numbers are the average of the test results of 10 samples. (Comparative Example 1) An electrolytic copper foil (rough-faced) produced under the same conditions as in Example 1. The surface roughness Rz was 4.5 // m. The surface roughness RZ of the glossy surface was 1.2 // m) 'This sample was further divided into two samples, and the same honing liquid (H3P〇3: 70vol%) as in Example 1 was used. , Water: 30vol%), let honing conditions be at current density: 10 ~ 20A / dm2, time: 30 ~ 6 0 seconds, voltage: 3V. The range is changed. For the above two samples, the electrolytic sugar honing of the coarse sugar surface of the electrolytic copper fan is performed, and the processing surface is subjected to the same fine roughening treatment as in the example. Samples 6 and 7 with final surface roughnesses of Rz4.2 // m and Rzl.O // m were produced. The rough surface side of the electrolytic copper foil of samples 6 and 7 obtained above was pressed on one side of the glass epoxy substrate to produce copper laminates of 12 areas. The paper size is applicable to Chinese National Standard (CNS) A4 specifications ( 210 X 297 public love) --- I ----------------- Order --------- line (Please read the precautions on the back before filling this page ) 574441 A7 B7 V. Description of the invention (U). A dry film is further laminated on the copper area laminate, and then a patterned film with a width of 100 // m and a circuit interval of 100 // m is used for UV exposure (please read the precautions on the back before filling this page) Make a circuit pattern. Next, it is etched with a copper chloride etchant. As a result, the lengths of the upper and lower bases of the $ wiring pattern are shown as 袠 i, respectively. Similarly, the etching factor (a / b) is also shown in the same table. In addition, these numbers are the average of the test results of 10 samples for each sample.

No. Surface roughness (Rz) (/ m) a (/ m) b (/ m) ^ Factor peel strength (kg / cm) Total evaluation 1 4.0 12 1.90 0.97 A Example 1 2 3.5 12 1.76 6.8 0.92 A 3 2.5 12 1.69 Ti 0.89 A 4 2.0 12 1.64 7.3 0.86 A 5 1.5 12 1.52 7.9 0.81 A Comparative Example 1 6 4.2 12 2.03 5.9 1.09 B 7 1.0 12 1.45 8.3 0.50 BA: Good, B: Defective according to Table 1 above It is obvious that the etching factor (a / b) in the examples (samples Nos. 1 to 5) of the present invention is good at 6.3 to 7.9, and becomes larger as the surface coarse sugar content (Rz) decreases. On the contrary, the peel strength is small, but the range of 0.97 to 0.81 kg / cm is still good. In terms of overall evaluation, it is excellent in peeling strength and etching factor. When a copper area laminate is etched to form a wiring pattern, it can effectively suppress the ladder-shaped etching phenomenon of the wiring cross section, and can obtain a substantially vertical 13 This paper size applies the Chinese National Standard (CNS) A4 specification (210 X 297 public love)-574441 A7 _B7__ V. Description of the invention) Etching surface can obtain electrolytic copper for copper area laminates suitable for forming fine-pitch wiring patterns Foil. On the other hand, the surface roughness Rz4.2 // m of the sample No. 6 of the comparative example has an etching factor of 5.9, which is a bad situation, and a trapezoidal etching phenomenon occurs on the wiring cross section. The surface roughness Rzl_0 // m of the sample No. 7 of the comparative example had a good etching factor, but had a problem that the peel strength was as low as 0.50 (kg / cm). Therefore, this sample No. 7 is not suitable as an electrolytic copper foil for copper area laminates. In the above, although the electrolytic honing of the rough surface of the electrolytic copper foil is mentioned, the processed surfaces are further finely divided. As an example of roughening treatment, even if the roughening treatment is not applied, even if the surface roughness Rz of the rough surface of the electrolytic copper foil is 1.5 to 4.0 // m, it still shows excellent peel strength and etching factor. [Effect of the Invention] The electrolytic copper foil for a copper area laminate of the present invention can effectively suppress the formation of a wiring pattern when the copper area laminate is etched to form a narrow and wide bottom cross section of the wiring cross section. The etching phenomenon of the ladder shape seen in the copper area laminate can obtain a substantially vertical etched surface, and an electrolytic copper foil for a copper area laminate suitable for the formation of a fine-pitch wiring pattern can be obtained. [Symbols] 1, 5 Top and 14 This paper size is applicable to Zhongguanjia Standard (CNS) A4 (21G X 297 meals) " (Please read the note on the back? Matters before filling out this page) · I 丨 丨丨 丨 丨 丨 Order—— 丨 -11-11 · 574441 A7 _ B7 V. Description of the invention () 2? 6 Bottom 3 Copper foil 4 Resin substrate (Please read the precautions on the back before filling this page) 15 Paper size Applicable to China National Standard (CNS) A4 (210 X 297 mm)

Claims (1)

574441 A8 B8 C8 D8 6. Scope of patent application (please read the precautions on the back before writing this page) 1. An electrolytic copper foil for copper area laminates, which uses electrolytic copper foil; it is characterized in that the electrolytic The surface roughness Rz of the rough surface of the copper foil is 1.5 ~ 4.0 // m. 2. For example, the electrolytic copper foil for copper area laminates according to item 1 of the patent application scope, wherein the surface roughness Rz of the rough surface of the electrolytic copper foil is 1.5 ~ 2.5 / zm 〇3. As the first or second application patent scope The electrolytic copper foil for copper area laminates according to this item, wherein the rough surface of the aforementioned electrolytic copper foil is an electrolytic honing surface or a chemical honing surface. 4. For example, the electrolytic copper foil for copper area laminates in the scope of patent application No. 3 is the one using electrolytic copper foil, wherein the rough surface of the electrolytic copper foil is electrolytically honing or chemically honing, and then further The electrolytic honing surface or the chemical honing surface is subjected to a roughening treatment so that the roughness Rz of the roughened surface becomes 1.5 to 4.0 // m 〇5. For example, the electrolytic copper foil for copper area laminates in the scope of patent application No. 4 , Where the roughness Rz of the roughened surface is 1.5 to 2.5 / zm. 6. For example, the electrolytic copper foil for copper area laminates in item 4 of the scope of patent application, wherein the size of the roughened particles is 1.5 / zm or less. 7. For the electrolytic copper foil for copper area laminates as claimed in item 5 of the scope of patent application, the particle size of the roughening treatment is as follows. 8. — A method for manufacturing electrolytic copper foil for copper area laminates, which is to perform electrolytic honing or chemical honing on the rough surface of the electrolytic copper foil, so that the surface roughness Rz of the rough surface of the electrolytic copper foil becomes 1.5 to 4.0. / zm. 9. For example, in the scope of patent application No. 8 of the electrolytic copper foil for copper area laminates, 1 ^ Paper size applies to China National Standard (CNS) A4 (210 X 297 mm) 1 ~ 574441 B8 C8 D8 Yuan (Please read the precautions on the back before writing this page) The manufacturing method is to perform electrolytic honing or chemical honing on the rough surface of the electrolytic copper foil so that the surface roughness Rz of the rough surface of the electrolytic copper foil becomes 1.5. ~ 2.5 // m 〇10. For the manufacturing method of electrolytic copper foil for copper area laminates according to item 9 of the scope of patent application, the rough surface of electrolytic copper foil is electrolytically honed or chemically honed, and then the electrolytic is further processed. The honing surface or the chemical honing surface is subjected to a roughening treatment so that the roughness Rz of the roughened surface becomes 1.5 to 4.0 // m. 11. If the method for manufacturing electrolytic copper foil for copper area laminates according to item 10 of the scope of patent application, set the roughness Rz of the roughened surface to 1.5 ~ 2.5 // m ° 12. If the scope of patent application is 10th or The method for producing an electrolytic copper foil for a copper area laminate according to Item 11, wherein the size of the roughened particles is 1.5 // m or less. 13. For the manufacturing method of electrolytic copper foil for copper area laminates according to item 10 or 11 of the scope of patent application, the electrolytic copper foil is manufactured by using an acidic copper sulfate solution having a sulfate ion concentration of 2 mg / l or less. 14. For the manufacturing method of electrolytic copper foil for copper area laminates according to item 12 of the application, the electrolytic copper foil is manufactured by using a sulfuric acid acid copper sulfate solution having a chloride ion concentration of 2 mg / l or less. 2 This paper size applies to China National Standard (CNS) A4 (210 X 297 mm)