Low-roughness copper foil with a high distribution density of copper nodules, a method for manufacturing the same, and a copper foil substrate containing low-roughness copper foil with a high distribution density of copper nodules.

Abstract

This invention provides a low-roughness copper foil with a high distribution density of copper nodules, a method for manufacturing the same, and a copper foil substrate containing the low-roughness copper foil with a high distribution density of copper nodules, which meet the requirements of high-frequency and high-speed transmission. [Solution] The copper foil comprises a main layer 1, a roughened plating layer 2, and at least one surface treatment layer 3. The main layer 1 has a basic flat surface 100, the roughened plating layer 2 is formed on the basic flat surface 100 and has a plurality of fine copper bumps 21, and at least one surface treatment layer 3 is formed on the roughened plating layer 2. The plurality of fine copper bumps 21 are uniformly distributed on the basic flat surface 100, and the basic flat surface 100 has a surface area of ​​1.0 μm 2 On average, there are 135 to 203 fine copper bumps 21 per area. The surface roughness Rz of the copper foil is less than 0.8 μm.

Description

[Technical Field]

[0001] The present invention relates to electrolytic copper foil, and more particularly to low-roughness copper foil with a high distribution density of copper bumps, which meets the requirements of high-frequency and high-speed transmission. [Background technology]

[0002] With the rapid development of the electronics and information industries, high-frequency and high-speed signal transmission has become a major consideration in the design and manufacture of copper foil. As is well known, the roughness (smoothness) of copper foil is a crucial factor affecting high-frequency and high-speed signal transmission. The rougher the copper foil, the slower the signal transmission speed and the worse the accuracy. Furthermore, excessively high roughness can cause signal transmission loss, affecting the transmission stability of high-frequency signals. Therefore, those skilled in the art related to copper foil usually pay attention to and control the roughness of the copper foil to ensure that the desired performance levels are reliably achieved in various applications.

[0003] However, in practical applications, a certain peel strength is required between the copper foil and the resin substrate to prevent delamination of the copper foil substrate (copper clad laminate, CCL) during subsequent processing and use. Generally, reducing the surface roughness of the copper foil also weakens the peel strength between the copper foil and the resin substrate, indicating that surface roughness and peel strength are conflicting indicators.

[0004] Therefore, overcoming the aforementioned drawbacks by improving the structural design to achieve extremely low roughness that approximates a smooth surface on the copper foil, while simultaneously maintaining peel strength between the copper foil and the resin substrate, is one of the important challenges for this project. [Overview of the project] [Problems that the invention aims to solve]

[0005] In this invention, copper bumps refer to fine, nodular copper roughening particles generated during the copper plating process. The technical problem that this invention aims to solve is to provide a low-roughness copper foil with a high distribution density of copper bumps, a method for manufacturing the same, and a copper foil substrate containing this low-roughness copper foil with a high distribution density of copper bumps, in response to the shortcomings of conventional technology. The low-roughness copper foil with a high distribution density of copper bumps of this invention can achieve low roughness while ensuring a certain peel strength. Furthermore, the low-roughness copper foil with a high distribution density of copper bumps of this invention is suitable for the manufacture of copper foil substrates, and printed circuit boards with high adhesion and excellent high-frequency transmission characteristics can be manufactured using the obtained copper foil substrate. [Means for solving the problem]

[0006] To solve the above technical problems, one of the technical means employed by the present invention is to provide a low-roughness copper foil with a high distribution density of copper nodules. The low-roughness copper foil with a high distribution density of copper nodules comprises a main layer, a roughening plating layer, and at least one surface treatment layer. The main layer has a basic flat surface, the roughening plating layer is formed on the basic flat surface and has a plurality of fine copper nodules, and at least one surface treatment layer is formed on the roughening plating layer. In the present invention, the plurality of fine copper nodules are uniformly distributed on the basic flat surface, and the basic flat surface has a density of 1.0 μm 2 It has an average of 135 to 203 microscopic copper bumps per area. The surface roughness Rz of low-roughness copper foil with a high distribution density of the aforementioned copper bumps is less than 0.8 μm.

[0007] To solve the above technical problems, another technical means employed by the present invention is to provide a method for manufacturing low-roughness copper foil with a high distribution density of copper nodules. The low-roughness copper foil with a high distribution density of copper nodules includes the steps of: forming a main body layer having a basic flat surface; forming a roughening plating layer containing a plurality of fine copper nodules on the basic flat surface; and forming at least one surface treatment layer on the roughening plating layer. In the present invention, the plurality of fine copper nodules are uniformly distributed on the basic flat surface, and the basic flat surface has a distribution of 1.0 μm 2It has an average of 135 to 203 microscopic copper bumps per area. Furthermore, the surface roughness Rz of low-roughness copper foil with a high distribution density of these copper bumps is less than 0.8 μm.

[0008] In an implementable or preferred embodiment of the present invention, the maximum particle size of each of the fine copper bumps is less than 100 nm.

[0009] In an implementable or preferred embodiment of the present invention, the roughness Rz of the basic flat surface is less than 0.5 μm, and the 60-degree gloss of the basic flat surface is greater than 400 GU.

[0010] In an implementable or preferred embodiment of the present invention, at least one surface treatment layer comprises a heat-resistant treatment layer formed on the roughened plating layer and a silane coupling agent layer formed on the heat-resistant treatment layer.

[0011] In an implementable or preferred embodiment of the present invention, the peel strength of a low-roughness copper foil with a high distribution density of copper bumps, as measured according to the IPC-TM-6502.4.8 standard, exceeds 3.5 lb / in.

[0012] In an implementable or preferred embodiment of the present invention, the step of forming the roughened plating layer includes roughening the main layer using a roughening solution, wherein the copper ion concentration in the roughening solution is 3 g / L to 25 g / L, the sulfuric acid concentration is 60 g / L to 150 g / L, and the concentration of at least one non-copper metal ion is 0.1 ppm to 300 ppm, and the at least one non-copper metal ion is selected from at least one metal ion from the group consisting of tungsten, tin, iron, cobalt, nickel, and molybdenum. Furthermore, the roughening treatment is performed at 1 A / dm 2 ~60A / dm 2 The process is carried out at a current density of 0.5 to 6 seconds.

[0013] To solve the above technical problems, another technical means employed in the present invention is to provide a copper foil substrate comprising a substrate and a low-roughness copper foil with a high distribution density of the aforementioned copper bumps placed on the surface of the substrate.

Advantages of the Invention

[0014] One of the advantageous effects of the present invention is that the low-roughness copper foil with a high distribution density of copper cob according to the present invention and its manufacturing method are such that "the main body layer has a substantially flat surface, and the plurality of the fine copper cobs are uniformly distributed on the substantially flat surface, and on the substantially flat surface, there are on average 135 to 203 fine copper cobs per area of 1.0 μm 2 and the surface roughness Rz of the low-roughness copper foil with a high distribution density of copper cob is less than 0.8 μm". By such technical features, it is possible to achieve an extremely low roughness approximating a smooth state on the copper foil surface, and at the same time, achieve both the peel strength between the copper foil and the resin base material. Furthermore, the low-roughness copper foil with a high distribution density of copper cob according to the present invention can maintain the signal integrity and reduce the signal transmission loss even in the application of 5G high-frequency and high-speed transmission.

Brief Description of the Drawings

[0015] [Figure 1] It is a flowchart of a low-roughness copper foil with a high distribution density of copper cob according to an embodiment of the present invention. [Figure 2] It is a schematic diagram showing the structure of a low-roughness copper foil with a high distribution density of copper cob according to the present invention. [Figure 3] It is a partial enlarged view of part III in FIG. 2. [Figure 4] It is an image obtained by observing the surface morphology of the low-roughness copper foil with a high distribution density of copper cob according to the present invention at 5,000 times using a scanning electron microscope. [Figure 5] It is an image obtained by observing the surface morphology of the low-roughness copper foil with a high distribution density of copper cob according to the present invention at 10,000 times using a scanning electron microscope. [Figure 6] It is an image obtained by observing the surface morphology of the low-roughness copper foil with a high distribution density of copper cob according to the present invention at 20,000 times using a scanning electron microscope. [Figure 7] It is an image obtained by observing the surface morphology of the low-roughness copper foil with a high distribution density of copper cob according to the present invention at 50,000 times using a scanning electron microscope. [Figure 8] It is a schematic diagram showing a copper foil substrate including a low-roughness copper foil with a high distribution density of copper cob according to an embodiment of the present invention.

Embodiments for Carrying out the Invention

[0016] In order to further deepen the understanding of the features and technical content of the present invention, embodiments of the present invention will be described below and the accompanying drawings will be shown. However, the accompanying drawings are only shown for reference and do not limit the scope of the claims of the present invention.

[0017] Hereinafter, the implementation manner of "low-roughness copper foil with a high distribution density of copper cob, its manufacturing method, and a copper foil substrate including a low-roughness copper foil with a high distribution density of copper cob" according to the present invention will be described according to a predetermined specific embodiment, and those skilled in the art can understand the advantages and effects of the present invention based on the content disclosed in this specification. The present invention can be implemented or applied by other different specific embodiments, and for each detail in this specification, various modifications and changes can be made based on different viewpoints and uses without departing from the concept of the present invention. It should be explained in advance that the accompanying drawings of the present invention are simple schematic explanations and are not drawn based on actual sizes. The technical content of the present invention will be described in more detail based on the following embodiments, but the protection scope of the present invention is not limited by the disclosed content.

[0018] It should be understood that in this specification, terms such as "first", "second", "third", etc. may be used to describe various elements or signals, but these elements or signals are not limited by these terms. These terms are mainly used to distinguish one element from another element, or one signal from another signal. Also, the term "or" used in this specification may include any one or a combination of multiple of the items listed in relation according to the actual situation.

[0019] Unless otherwise specified, terms used in this invention are synonymous with those commonly understood by those skilled in the art. The materials used in the following embodiments are commercially available materials or materials manufactured by the prior art unless otherwise specified. The methods or operations used in the following examples are common methods or operations in the art unless otherwise specified.

[0020] As shown in Figure 1, the present invention provides a method for manufacturing low-roughness copper foil with a high distribution density of copper bumps, comprising the steps of: step S1 for forming a main body layer of copper foil; step S2 for roughening the main body layer of copper foil; and step S3 for surface treatment of the roughened main body layer of copper foil. Furthermore, as shown in Figure 2, the low-roughness copper foil Z with a high distribution density of copper bumps obtained using the manufacturing method of the present invention comprises a main body layer 1 (raw foil layer), a roughened plating layer 2, and at least one surface treatment layer 3. The main body layer 1 has a basic flat surface 100, that is, there are no obvious peaks or valleys in the surface morphology of the main body layer 1. The roughened plating layer 2 is formed on the basic flat surface 100 and contains a plurality of fine copper bumps 21, and at least one surface treatment layer 3 is formed on the roughened plating layer 2.

[0021] Furthermore, Figures 4 to 7 are images of the surface morphology of the copper foil observed using a Hitachi scanning electron microscope SU8220 at magnifications of 5,000x, 10,000x, 20,000x, and 50,000x under an acceleration voltage of 10.0kV. As shown in Figures 3 to 6, the multiple fine copper bumps 21 are uniformly distributed on the basic flat surface 100 of the main layer 1, and the maximum particle size of each of the fine copper bumps 21 is less than 100 nm. Moreover, the surface roughness Rz of the low-roughness copper foil Z with a high distribution density of copper bumps in the present invention is less than 0.8 μm. Notably, the present invention, through the above technical means, helps to smooth the surface of the copper foil, reduce the surface roughness of the copper foil, and maintain the peel strength between the copper foil and the resin substrate at an industry-acceptable level.

[0022] The following describes in detail each step of the manufacturing method of the present invention with reference to the drawings.

[0023] In step S1 of Figure 1, the main body layer 1 (raw foil layer) may be formed by electrolytic extraction, where the action of an electric field moves copper ions in the copper sulfate electrolyte to the surface of the cathode roller and deposits them, forming a continuous and uniform copper layer. In the embodiment of the present invention, the thickness of the main body layer 1 is in the range of 9 μm to 70 μm, and the roughness Rz of the basic flat surface 100 of the main body layer 1 may be 0.5 μm or less, and preferably less than 0.5 μm. The 60-degree gloss of the basic flat surface 100 of the main body layer 1 exceeds 400 GU. Notably, by controlling the roughness Rz and gloss of the basic flat surface 100 of the main body layer 1, the roughened plating layer 2 formed in step S2 has characteristics such as a high surface area and low roughness that meet the requirements of high-frequency and high-speed transmission.

[0024] In step S2, the main layer 1 is roughened using a roughening solution, that is, the main layer 1 is electrolyzed with a copper sulfate-based roughening solution under conditions of high current density, so that the scattered metallic copper deposits on the basic flat surface 100 of the main layer 1 grow into a plurality of uniformly distributed fine copper nodules 21. In the embodiment of the present invention, the basic flat surface 100 of the main layer 1 has 1.0 μm 2 The surface area contains an average of 135 to 203 micro-copper nodules 21, preferably 120 to 180. The number of copper nodules per unit area can be calculated by analyzing the SEM image in Figure 6 using Image-Pro software.

[0025] Furthermore, a formulation with a high copper sulfate ratio is adopted as the roughening solution. The copper ion concentration in the roughening solution is 3 g / L to 25 g / L, the sulfuric acid concentration is 60 g / L to 150 g / L, and the concentration of at least one non-copper metal ion is 0.1 ppm to 300 ppm. At least one of the non-copper metal ions is selected from at least one metal ion in the group consisting of tungsten (W), tin (Sn), iron (Fe), cobalt (Co), nickel (Ni), and molybdenum (Mo). When the copper ion concentration is 3 g / L to 25 g / L, the copper crystal grains basically grow horizontally, resulting in excellent uniformity of the formed roughened plating layer 2 and excellent roughening effect. When the sulfuric acid concentration is 60 g / L to 150 g / L, the uniformity of the roughened plating layer 2 can be improved, which has a positive impact on increasing the peel strength and reducing the powder falling on the copper foil surface. By adding the non-copper metal ions as described above, the mechanism of copper precipitation or the crystal form can be changed, which also has a positive impact on increasing the peel strength and reducing the powder falling on the copper foil surface.

[0026] Also, the operating conditions of the roughening treatment are that the current density is controlled within the range of 1 A / dm 2 ~60 A / dm 2 and preferably within the range of 20 A / dm 2 ~50 A / dm 2 The roughening treatment time is in the range of 0.5 seconds to 20 seconds, and preferably 0.5 seconds to 6 seconds. When using a relatively high current density, the copper crystal grains can be refined to form copper nodules with a small particle size. Also, when the current density is within the above range, the effect of electrolytic polishing can be obtained, and the roughness of the copper foil surface can be reduced.

[0027] In an embodiment, the current density of the roughening treatment is 1 A / dm 2 , 5 A / dm 2 , 10 A / dm 2 , 15 A / dm 2 , 20 A / dm 2 , 25 A / dm 2 , 30 A / dm 2 , 35 A / dm 2 , 40 A / dm 2 , 45 A / dm2 , 50A / dm 2 , 55A / dm 2 , or 60A / dm 2 The roughening treatment time may be 0.5 seconds, 1 second, 2 seconds, 3 seconds, 4 seconds, 5 seconds, or 6 seconds.

[0028] If necessary, the manufacturing method of the present invention may include multiple roughening treatments. For example, a second roughening treatment may be performed after the completion of the first roughening treatment (step S2), and the second roughening treatment may use the same treatment solution and operating conditions as the first roughening treatment.

[0029] Referring again to Figure 1 in conjunction with Figures 2 and 3, in step S3, the surface treatment performed on the roughened main body layer 1 may include heat-resistant treatment and silane coupling agent treatment. In the embodiment of the present invention, the copper foil becomes able to withstand the high temperatures of the process (such as thermocompression bonding) by performing heat-resistant treatment on the roughened main body layer 1 using a nickel and / or zinc-containing treatment solution to form a heat-resistant treatment layer 31 on the roughened plating layer 2. After the heat-resistant treatment is completed, the heat-resistant main body layer 1 is treated with a silane coupling agent using a treatment solution containing a silane coupling agent to form a silane coupling agent layer 32 on the heat-resistant treatment layer 31, thereby providing stronger adhesion between the copper foil and the resin substrate. The peel strength of the copper foil after silane coupling agent treatment, as measured according to the IPC-TM-6502.4.8 standard, exceeds 3.5 lb / in.

[0030] Furthermore, in the heat-resistant treatment, the roughened main layer 1 is placed in a treatment solution containing nickel and / or zinc, and electrolysis is performed under relatively low current density conditions to form a heat-resistant treatment layer 31 as a heat shield layer to protect the roughened fine copper bumps 21, and the fine copper bumps 21 are surrounded and reinforced by the formed heat-resistant treatment layer 31. Notably, the maximum particle size of the fine copper bumps 21 formed in step S2 is less than 100 nm, and the strong bond between the fine copper bumps 21 and the main layer 1 can be maintained solely by relying on the heat-resistant treatment layer 31. Therefore, even if the fixing treatment step is omitted, the fine copper bumps 21 can be firmly fixed to the basic flat surface 100 of the main layer 1, preventing powder from falling off the copper foil surface. If necessary, the roughened surface of the copper foil may be washed with water before the heat-resistant treatment.

[0031] Furthermore, in the silane coupling agent treatment, the roughened surface of the copper foil may be brought into uniform contact with the treatment solution containing the silane coupling agent by coating or immersion, and then air-dried or heat-dried. Suitable silane coupling agents for the present invention include epoxy silanes, amino silanes, vinyl silanes, methacrylic silanes, acrylic silanes, styrene silanes, urea silanes, mercapto silanes, thioether silanes, and isocyanate silanes, with amino silanes and vinyl silanes being preferred. If necessary, the roughened surface of the copper foil may be washed with water before the silane coupling agent treatment.

[0032] In actual application, in step S3, a different surface treatment may be performed on the copper foil before the heat-resistant treatment, or between the heat-resistant treatment and the silane coupling agent treatment. Examples include corrosion-resistant treatment, oxidation-preventive treatment, and / or passivation treatment, but the present invention is not limited to these.

[0033] The technical effects of the present invention will be described below with reference to several embodiments, but the present invention is not limited to the embodiments described.

[0034] [Table 1] TIFF2026100768000002.tif99140

[0035] Table 1 shows the maximum particle size and distribution density of copper nodules in the copper foil samples of each example. The images were obtained by observing the surface morphology of the copper foil with a scanning electron microscope at a magnification of 50,000x using Image-Pro software. The particle size distribution of the copper nodules was analyzed, and the number of copper nodules per unit area was calculated. Specifically, using an image of the surface morphology of a 10 μm × 10 μm copper foil observed with a scanning electron microscope at a magnification of 50,000x using Image-Pro software, the software can automatically calculate the number and particle size of the copper nodules. It should be noted that the maximum particle size in this application is the equivalent circular diameter of the copper nodules in the image. The surface roughness Rz of the copper foil samples of each example was measured with a Keyence VK-X1000 laser microscope at a magnification of 1,000x. The measured values ​​were obtained by averaging the values ​​taken at 3 to 5 randomly selected locations on the copper foil surface, and the values ​​obtained in the examples of this application (shown in Table 1) are the average of three measured values. Furthermore, the peel strength between the copper foil sample and the resin substrate for each example was measured based on the international standard IPC-TM-650.

[0036] As shown in Figure 8, the low-roughness copper foil Z of the present invention, which has a high distribution density of copper bumps, is suitable for manufacturing copper foil substrates (copper-clad laminates), and the resulting copper foil substrates can be used to manufacture printed circuit boards with high adhesion and excellent high-frequency transmission characteristics. Furthermore, by thermocompression bonding, a predetermined number of resin substrates S (e.g., prepregs) can be laminated between two low-roughness copper foils Z with a high distribution density of copper bumps to manufacture a copper foil substrate with copper foil on both sides. In addition, the low-roughness copper foil Z with a high distribution density of copper bumps can be patterned by known processes to form a fine pitch.

[0037] [Advantageous effects of the embodiment] One of the advantageous effects of the present invention is that the low-roughness copper foil and its manufacturing method according to the present invention, which have a high distribution density of copper bumps, "the main body layer has a basic flat surface, the plurality of fine copper bumps are uniformly distributed on the basic flat surface, and the basic flat surface has a distribution density of 1.0 μm 2 The technical features of the low-roughness copper foil, such as having an average of 135 to 203 microscopic copper bumps per area and having a surface roughness Rz of less than 0.8 μm due to the high distribution density of these copper bumps, enable the achievement of extremely low roughness that approximates a smooth surface while simultaneously maintaining peel strength between the copper foil and the resin substrate. Furthermore, the low-roughness copper foil with a high distribution density of copper bumps according to the present invention can maintain signal integrity and reduce signal transmission loss even in applications of 5G high-frequency and high-speed transmission.

[0038] Furthermore, in the low-roughness copper foil with a high distribution density of copper bumps according to the present invention, the maximum particle size of each of the fine copper bumps is less than 100 nm. Therefore, even if the fixing process is omitted, the copper bumps can be fixed, the copper bumps and the main layer of the copper foil are firmly bonded, and powder shedding from the copper foil surface can be prevented.

[0039] The information disclosed above represents only preferred and implementable embodiments of the present invention, and the claims of the present invention are not limited thereto. Therefore, any equivalent technical modifications made using the description and drawings of the present invention are all included within the scope of the claims of the present invention. [Explanation of Symbols]

[0040] S Resin base material Low-roughness copper foil with a high distribution density of Z copper bumps. 1. Main body layer 100 Basic flat surfaces 2. Roughened plating layer 21 Fine copper bumps 3. Surface treatment layer 31 Heat-resistant treatment layer 32 Silane coupling agent layer S1, S2, S3 manufacturing process

Claims

1. A main body layer having a basic flat surface, A roughened plating layer formed on the aforementioned basic flat surface and having a plurality of fine copper bumps, A low-roughness copper foil having a high distribution density of copper bumps, comprising at least one surface treatment layer formed on the roughened plating layer, Multiple of the aforementioned fine copper bumps are uniformly distributed on the basic flat surface, and the basic flat surface has a thickness of 1.0 μm. 2 It has an average of 135 to 203 microscopic copper nodules per area. A low-roughness copper foil with a high distribution density of copper nodules, characterized in that the surface roughness Rz of the low-roughness copper foil with a high distribution density of copper nodules is less than 0.8 μm.

2. The low-roughness copper foil with a high distribution density of copper bumps, wherein the maximum particle diameter of each of the fine copper bumps is less than 100 nm, as described in claim 1.

3. The low-roughness copper foil according to claim 1, wherein the roughness Rz of the basic flat surface is less than 0.5 μm, and the 60-degree gloss of the basic flat surface exceeds 400 GU, wherein the distribution density of copper bumps is high.

4. The low-roughness copper foil with a high distribution density of copper bumps according to claim 1, wherein at least one of the surface treatment layers comprises a heat-resistant treatment layer formed on the roughened plating layer and a silane coupling agent layer formed on the heat-resistant treatment layer.

5. The low-roughness copper foil with a high distribution density of copper bumps, as described in claim 4, wherein the peel strength measured according to the IPC-TM-6502.4.8 standard for low-roughness copper foil with a high distribution density of copper bumps exceeds 3.5 lb / in.

6. A step of forming a main body layer having a basic flat surface, A step of forming a roughened plating layer containing multiple fine copper bumps on the basic flat surface, A method for manufacturing low-roughness copper foil having a high distribution density of copper bumps, comprising the step of forming at least one surface treatment layer on the roughened plating layer, Multiple of the aforementioned fine copper bumps are uniformly distributed on the basic flat surface, and the basic flat surface has a thickness of 1.0 μm. 2 It has an average of 135 to 203 microscopic copper bumps per area. A method for producing low-roughness copper foil with a high distribution density of copper nodules, characterized in that the surface roughness Rz of the low-roughness copper foil with a high distribution density of copper nodules is less than 0.8 μm.

7. In the step of forming the roughened plating layer, the maximum particle size of each of the fine copper bumps is less than 100 nm, as described in claim 6, for manufacturing a low-roughness copper foil with a high distribution density of copper bumps.

8. The step of forming the roughened plating layer includes roughening the main layer using a roughening solution, wherein the copper ion concentration in the roughening solution is 3 g / L to 25 g / L, the sulfuric acid concentration is 60 g / L to 150 g / L, and the concentration of at least one non-copper metal ion is 0.1 ppm to 300 ppm, and the at least one non-copper metal ion is selected from at least one metal ion from the group consisting of tungsten, tin, iron, cobalt, nickel, and molybdenum. The aforementioned roughening treatment is 1 A / dm 2 ~60A / dm 2 A method for producing low-roughness copper foil with a high distribution density of copper bumps, according to claim 7, wherein the roughening treatment is performed at a current density and the duration of the roughening treatment is 0.5 to 6 seconds.

9. A method for producing a low-roughness copper foil with a high distribution density of copper bumps, according to claim 6, wherein the step of forming at least one of the surface treatment layers includes forming a heat-resistant treatment layer on the roughened plating layer and forming a silane coupling agent layer on the heat-resistant treatment layer.

10. A method for producing low-roughness copper foil with a high distribution density of copper bumps, according to claim 6, wherein the roughness Rz of the basic flat surface in the step of forming the main body layer is less than 0.5 μm, and the 60-degree gloss of the basic flat surface exceeds 400 GU.

11. A copper foil substrate comprising a substrate and a low-roughness copper foil with a high distribution density of copper bumps as described in claim 1, which is placed on the surface of the substrate.

Images