Heat-resistant surface-treated copper foil, copper foil laminates containing the same, and printed circuit boards.

Abstract

The present invention provides a surface-treated copper foil having a surface treatment layer including a primary particle layer containing Cu or Cu alloy particles formed on at least one surface of an original copper foil, and a secondary particle layer containing Zn particles formed on the primary particle layer, the secondary particle layer being composed of particle clusters formed by a plurality of Zn particles gathering together.

Description

[Technical Field]

[0001] The present invention relates to surface-treated copper foil, and more particularly to surface-treated copper foil that has long-term high-temperature reliability on resin substrates and low transmission loss, making it suitable for use in high-frequency circuits, as well as copper foil laminates and printed circuit boards containing the same. [Background technology]

[0002] As the miniaturization and weight reduction of electrical and electronic equipment accelerates, printed circuits formed on substrates are becoming smaller, more integrated, and more compact. This, in turn, demands a variety of physical properties from the copper foil used in printed circuit boards.

[0003] The composite materials used in the manufacture of flexible substrates, high-density mounting multilayer substrates, high-frequency circuit boards, etc. (hereinafter collectively referred to as "circuit boards" or "printed wiring boards") consist of a conductor (copper foil) and an insulating substrate (including a resin film) that supports it. The insulating substrate ensures insulation between the conductors and has sufficient strength to support the components.

[0004] To improve the adhesive strength between an insulating substrate and copper foil, it is common practice to attach roughening particles to the surface of the copper foil to enhance adhesion through an anchoring effect. However, since copper foil for high-frequency circuits requires low-roughness surface-treated copper foil, this method has the problem of being difficult to ensure sufficient adhesive strength with resin substrates. In particular, the bonding surface between the copper foil and the insulating substrate is formed by high-temperature processes such as heat bonding or exposure to high-temperature environments, but ensuring high-temperature reliability of the adhesive strength between the copper foil and the substrate is extremely difficult in practice.

[0005] To address these problems, attempts have been made to use heat-resistant resin substrates such as polytetrafluoroethylene (PTFE) resin and to impart heat resistance to conventional Cu particle layers by adding various alloy layers.

[0006] However, such alloy layers have drawbacks: they reduce the etching rate and increase transmission loss, and although they have some heat resistance, it is difficult to ensure long-term high-temperature reliability. [Overview of the project] [Problems that the invention aims to solve]

[0007] To solve the problems of the conventional technology described above, the present invention aims to provide a surface-treated copper foil that has high adhesive strength to a resin substrate at high temperatures, long-term high-temperature reliability of adhesive strength, and is suitable as a high-frequency foil, a copper foil laminate containing the same, and a printed circuit board containing the same. [Means for solving the problem]

[0008] To achieve the above technical objectives, the present invention provides a surface-treated copper foil having a surface treatment layer comprising a primary particle layer containing Cu or Cu alloy particles formed on at least one surface of a copper foil, and a secondary particle layer containing Zn particles formed on the primary particle layer, wherein the secondary particle layer consists of particle clusters formed by the aggregation of a plurality of Zn particles.

[0009] In the present invention, the particle aggregate may be distributed discontinuously on the first particle layer.

[0010] In the present invention, the surface treatment layer of the surface-treated copper foil may have a surface roughness (Rz) of 1.0 μm or less.

[0011] In the present invention, the particle aggregates may be distributed in an average of 2 to 15 particles per 5 μm × 5 μm area of ​​the surface-treated copper foil.

[0012] In the present invention, the particle size of the secondary particle layer may be larger than the particle size of the primary particle layer.

[0013] In the present invention, the average particle size of the primary particle layer is preferably less than 100 nm. Also, in the present invention, the particle aggregates of the secondary particle layer preferably have an average size of 0.5 μm to 2.0 μm.

[0014] In the present invention, the Zn concentration of the surface treatment layer is preferably 2000 μg / dm 2 or more, and preferably 3500 μg / dm 2 or less.

[0015] The surface-treated copper foil of the present invention may further include a rust preventive layer on the second particle layer, and the rust preventive layer preferably contains chromium.

[0016] In the present invention, the copper foil substrate is preferably an electrolytic copper foil.

[0017] Also, in order to achieve the above other technical problems, the present invention provides a copper foil laminate in which the above surface-treated copper foil is laminated on a resin substrate. At this time, the resin substrate may be a PTFE substrate.

[0018] In the present invention, the copper foil laminate preferably has a high-temperature deterioration rate of the adhesive strength of less than 10%.

[0019] The present invention also provides a printed wiring board formed using the above copper foil laminate.

Advantages of the Invention

[0020] According to the present invention, it is possible to provide a surface-treated copper foil having a high adhesive strength with a resin substrate at high temperatures, having long-term high-temperature reliability of the adhesive strength, and being suitable as a high-frequency foil, a copper foil laminate including the same, and a printed wiring board including the same.

Brief Description of the Drawings

[0021] [Figure 1] It is an electron microscope photograph of a cross section of a surface-treated copper foil according to an embodiment of the present invention. [Figure 2]This is an electron microscope image of the surface of a surface-treated copper foil according to one embodiment of the present invention. [Figure 3A] This is an electron microscope image of the surface of the surface-treated copper foil manufactured according to the example. [Figure 3B] This is an electron microscope image of the surface of a surface-treated copper foil manufactured by the comparative example. [Modes for carrying out the invention]

[0022] The embodiments and configurations shown in the drawings described herein represent only one of the most preferred embodiments of the present invention and do not represent the entire technical concept of the invention. Therefore, it should be understood that there are various equivalents and modifications that can substitute for them at the time of filing. Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0023] The surface-treated copper foil of the present invention comprises a base foil, a primary particle layer on at least one surface of the base foil, and a secondary particle layer on the primary particle layer. Furthermore, the surface-treated copper foil of the present invention may further include a rust-preventive layer on the secondary particle layer.

[0024] Figures 1 and 2 are electron microscope images of the cross-sectional structure and surface structure of a surface-treated copper foil according to one embodiment of the present invention, respectively.

[0025] Referring to Figure 1, a multilayer surface treatment layer consisting of a primary particle layer 20 and a secondary particle layer 30 is formed on one side surface of the base foil 10. From the photograph in Figure 1, it can be seen that the primary particle layer 20 covers virtually the entire surface of the base foil, while the secondary particle layer 30 is discontinuously distributed on the primary particle layer 20.

[0026] Referring to Figure 2, we can see a secondary particle layer 30 consisting of particle clusters with an average size of 0.5 μm to 2 μm that appear relatively bright, and a primary particle layer 20 consisting of fine particles smaller than 0.1 μm that appear dark and form the background of the secondary particle layer. Here, the primary particle layer is composed of Cu particles, and the secondary particle layer is composed of Zn particles.

[0027] The particle aggregates in the secondary particle layer consist of coarse Zn particles that are 2 to 5 times larger than those in the primary particle layer, even though the individual particles are less than 0.5 μm in size. These particles form a clustered structure resembling bunches of grapes. While some single particles are observed in the secondary particle layer, the majority consist of clusters of two or more particles. These clusters have an average size of 0.5 μm to 2 μm. In this invention, the particle clusters are formed in localized regions, and some are isolated from each other.

[0028] The following describes in detail the base foil, primary particle layer, secondary particle layer, rust-preventive layer, and methods for manufacturing them according to the present invention.

[0029] A. Original foil

[0030] In this invention, the raw copper foil refers to copper foil that has not undergone surface treatment or rust prevention treatment. Any known copper foil can be used as the raw copper foil. In one example, the untreated copper foil may be electrolytic copper foil or rolled copper foil.

[0031] In the present invention, the thickness of the base foil is not particularly limited, but when surface-treated copper foil is used in a printed circuit board, the thickness of the base foil may be, for example, 6 μm to 35 μm, preferably 7 μm to 17 μm.

[0032] In this invention, the raw foil is 35 kgf / mm 2 ~60kgf / mm 2 , 35 kgf / mm 2 ~50 kgf / mm 2 , or 35 kgf / mm 2 ~45 kgf / mm² 2 It is preferable that it has a tensile strength of [value].

[0033] In addition, in the present invention, in the bonding process of the raw foil with a prepreg for forming a copper foil laminate or a printed wiring board, it is preferable that the mechanical properties of the raw foil before and after high-temperature pressing are kept constant. In the present invention, the change in crystal grains of the raw foil before and after pressing is very small.

[0034] For example, with respect to the tensile strength value at room temperature, the rate of change of the tensile strength value after heat treatment at a pressure of 4.9 Mpa and a temperature of 220 °C for a predetermined time may be less than 5%, or less than 3%. Further, with respect to the elongation rate at room temperature, the rate of change of the elongation rate after heat treatment at a pressure of 4.9 Mpa and a temperature of 220 °C for a predetermined time may be less than 5%, or less than 3%.

[0035] B. Primary particle layer (nodule layer)

[0036] In the present invention, the primary particle layer may be formed on one or both surfaces of the raw foil. The surface treatment method for forming the surface treatment layer of the present invention is not particularly limited. For example, the raw foil can be electroplated to form a surface treatment layer. As the electrolytic solution, an aqueous solution containing 5 to 60 g / L of a copper salt and 50 to 200 g / L of disodium ethylenediaminetetraacetate (EDTA-2Na), adjusted to, for example, pH 1 to 8 (for example, pH 6 to 7), can be used. Examples of the type of copper salt include copper sulfate (CuSO4), copper nitrate (Cu(NO3)2), copper chloride (CuCl2), copper acetate (Cu(CH3COO)2), etc. As additives, at least one selected from the group consisting of citric acid (C6H8O7), ethylenediaminetetraacetic acid (C 10 H 16 N2O8), nitrilotriacetic acid (C6H9NO6), sodium citrate (C6H5Na3O7), tartaric acid (C4H6O6) can be used, but it is not limited thereto. The electroplating is carried out, for example, by immersing an untreated raw foil as the cathode in an electrolytic solution with an insoluble electrode as the anode, and electrolyzing at a liquid temperature of 25 to 45 °C and a current density of 0.5 to 10 A / dm 2 for, for example, 5 to 20 seconds, but it is not limited thereto.

[0037] In the present invention, the primary particle layer is preferably composed of fine copper particles having an average particle size of 100 nm or less. For example, the fine copper particles of the primary particle layer may have an average particle size of 10 nm to 100 nm, 20 nm to 100 nm, or 50 nm to 100 nm. In the present invention, the average particle size of the copper particles can be calculated by obtaining a scanning electron microscope (SEM) image and measuring the particle size of the copper particles by image analysis, or it may be calculated by averaging the measured values ​​of a total of 100 particles. When the average particle size of the fine copper particles of the primary particle layer falls within this range, it exhibits excellent adhesion strength to the resin substrate and low transmission loss, making it suitable as a high-frequency foil.

[0038] C. Secondary particle layer

[0039] The secondary particle layer can be formed by electroplating the surface-treated foil on which the primary particle layer has been formed. An aqueous solution containing 1-5 g / L zinc and 1-5 g / L phosphoric acid is used as the electrolyte. The surface-treated foil is immersed in the electrolyte as the cathode, and the solution temperature is 25-45°C and the current is 1-3 A / dm². 2 At this current density, electrolysis may be performed for, for example, 5 to 10 seconds, but is not limited to this.

[0040] D. Rust-preventive layer

[0041] In the present invention, a rust-preventive layer may be formed on the secondary particle layer. The rust-preventive layer may contain chromium (Cr). The rust-preventive layer may contain metals such as nickel (Ni), zinc (Zn), cobalt (Co), titanium (Ti), and tin (Sn) in place of or in addition to chromium.

[0042] In the present invention, for chromate rust prevention treatment, an electrolyte solution containing 1 to 5 g / l of chromium is used, with a liquid temperature of 25 to 35°C and a current of 0.5 A / dm 2 This may be done by plating for 1 to 5 seconds at a given current density, followed by a water rinse.

[0043] In the present invention, the surface-treated copper foil may be bonded to a low-dielectric resin, polyimide, hydrocarbon, or polytetrafluoroethylene film to be manufactured as a copper foil laminate.

[0044] In the present invention, the surface roughness (Rz) of the surface-treated copper foil is preferably less than 1.0 μm, and more preferably in the range of 0.85 to 0.95. Furthermore, in the present invention, the 3D roughness (Sa) of the surface-treated copper foil is preferably 0.3 or higher, and more preferably in the range of 0.3 to 0.35.

[0045] The surface-treated copper foil described above can be used as a copper foil laminate by laminating it onto a resin substrate, and such a copper foil laminate may be used to manufacture printed circuit boards.

[0046] In the present invention, the surface-treated copper foil exhibits high adhesive strength to resin substrates such as low-dielectric resins, polyimides, hydrocarbons, or polytetrafluoroethylenes, and the possibility of deterioration of adhesive strength is very low even when exposed to high temperatures for a long period of time.

[0047] The surface-treated copper foil of the present invention may have an adhesive strength to PTFE resin of 2.0 kgf / cm or more, 2.5 kgf / cm or more, 2.7 kgf / cm or more, or 2.8 kgf / cm or more. In this case, the adhesive strength may be measured in accordance with JIS C6481.

[0048] The surface-treated copper foil of the present invention is preferably manufactured by bonding a copper foil laminate with a resin substrate such as PTFE resin, and the adhesive strength degradation rate (%), which corresponds to the rate of change in adhesive strength after 10 days at a temperature of 177°C, based on the adhesive strength value after 1 day, is 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, or 5% or less. [Examples]

[0049] The present invention will be described in more detail below with reference to examples. However, these are presented as preferred examples of the present invention and should not be construed as limiting the present invention in any way.

[0050] Examples

[0051] <Example 1>

[0052] A 12 μm thick raw foil (electrolytic copper foil) is immersed in an aqueous solution containing 10-20 g / L of copper and 100-200 g / L of EDTA-2Na, at a liquid temperature of 25°C, pH 7, and current density of 8 A / dm². 2 Plating was performed for 4 seconds under these conditions to form a primary particle layer (nodule layer).

[0053] Next, the copper foil with the primary particle layer formed on it is immersed in an aqueous solution of zinc sulfate (zinc concentration 1-5 g / L) and phosphoric acid 1-5 g / L, and then subjected to a 3.5 A / dm² test. 2 The copper foil was treated twice for 6 seconds under the specified conditions to form a secondary particle layer. Subsequently, the surface-treated copper foil was immersed in an aqueous solution of chromium with a concentration of 2 g / L for 3 seconds, followed by rinsing with water to form a rust-preventive layer. Next, the rust-preventively treated copper foil was immersed in a solution of silane coupling agent with a concentration of 1 to 10 g / L for 3 seconds, followed by drying with hot air at a temperature of 100°C to produce surface-treated copper foil.

[0054] <Example 2>

[0055] A 12 μm thick raw foil was immersed in an aqueous solution containing 10-20 g / L of copper and 100-200 g / L of EDTA-2Na, at a liquid temperature of 25°C, pH 7, and current density of 8 A / dm². 2 Plating was performed for 4 seconds under these conditions to form a primary particle layer (nodule layer).

[0056] Next, the copper foil with the primary particle layer formed on it is immersed in an aqueous solution of 1-5 g / L zinc and 1-5 g / L phosphoric acid, and subjected to a 2.5 A / dm² solution. 2The copper foil was treated twice for 6 seconds under the specified conditions to form a secondary particle layer. Subsequently, the surface-treated copper foil was immersed in an aqueous solution of chromium with a concentration of 2 g / L for 3 seconds, followed by rinsing with water to form a rust-preventive layer. Next, the rust-preventively treated copper foil was immersed in a solution of silane coupling agent with a concentration of 1 to 10 g / L for 3 seconds, followed by drying with hot air at a temperature of 100°C to produce surface-treated copper foil.

[0057] <Comparative Example 1>

[0058] A 12 μm thick raw foil was immersed in an aqueous solution containing 10-20 g / L of copper and 100-200 g / L of EDTA-2Na, at a liquid temperature of 25°C, pH 7, and current density of 8 A / dm². 2 Plating was performed for 4 seconds under these conditions to form a primary particle layer (nodule layer).

[0059] Next, the copper foil with the primary particle layer formed on it is immersed in an aqueous solution of 1-5 g / L zinc and 1-5 g / L phosphoric acid, and subjected to a 2.0 A / dm² solution. 2 The copper foil was treated twice for 6 seconds under the specified conditions to form a secondary particle layer. Subsequently, the surface-treated copper foil was immersed in an aqueous solution of chromium with a concentration of 2 g / L for 3 seconds and then washed with water to form a rust-preventive layer. Next, the rust-preventively treated copper foil was immersed in a solution of silane coupling agent with a concentration of 1 to 10 g / L for 3 seconds and then dried with hot air at a temperature of 100°C to produce surface-treated copper foil.

[0060] <Comparative Example 2>

[0061] A 12 μm thick raw foil was immersed in an aqueous solution containing 10-20 g / L of copper and 100-200 g / L of EDTA-2Na, at a liquid temperature of 25°C, pH 7, and current density of 8 A / dm². 2 Plating was performed for 4 seconds under these conditions to form a primary particle layer (nodule layer).

[0062] Next, the copper foil with the primary particle layer formed on it is immersed in an aqueous solution of 1-5 g / L zinc and 1-5 g / L phosphoric acid, and then subjected to 0.5 A / dm 2The copper foil was treated twice for 40 seconds under the specified conditions to form a secondary particle layer. Subsequently, the surface-treated copper foil was immersed in an aqueous solution of chromium with a concentration of 2 g / L for 3 seconds and then washed with water to form a rust-preventive layer. Next, the rust-preventively treated copper foil was immersed in a solution of silane coupling agent with a concentration of 1 to 10 g / L for 3 seconds and then dried with hot air at a temperature of 100°C to produce surface-treated copper foil.

[0063] <Comparative Example 3>

[0064] A 12 μm thick raw foil was immersed in an aqueous solution containing 10-20 g / L of copper and 100-200 g / L of EDTA-2Na, at a liquid temperature of 25°C, pH 7, and current density of 8 A / dm². 2 Plating was performed for 4 seconds under these conditions to form a primary particle layer (nodule layer). Then, 60-70 g / L of copper, 120 g / L of sulfuric acid, and 15 A / dm³ were used. 2 Under these conditions, a covering plating was applied for 3 seconds to prevent the nodules from falling off.

[0065] Next, the covering plated copper foil is immersed in an aqueous solution of 1-5 g / L zinc and 1-5 g / L phosphoric acid, and subjected to 0.3 A / dm 2 The copper foil was treated twice for 6 seconds under the specified conditions to form a secondary particle layer. Subsequently, the surface-treated copper foil was immersed in an aqueous solution of chromium with a concentration of 2 g / L for 3 seconds and then washed with water to form a rust-preventive layer. Next, the rust-preventively treated copper foil was immersed in a solution of silane coupling agent with a concentration of 1 to 10 g / L for 3 seconds and then dried with hot air at a temperature of 100°C to produce surface-treated copper foil.

[0066] <Evaluation of physical properties>

[0067] The physical properties of each surface-treated copper foil sample produced in the examples and comparative examples were measured. The physical property evaluation items and measurement methods are as follows.

[0068] a. Roughness

[0069] For the surface-treated copper foils produced in the examples and comparative examples, the 10-point average roughness R of the copper foil before and after surface treatment was measured using a surface roughness measuring instrument SURFCOM 1400D (TSK, Tokyo Seimitsu) in accordance with JIS B0601. zWe measured it.

[0070] b. 3D roughness

[0071] For the surface-treated copper foils produced in the examples and comparative examples, the shape of minute steps on the material was measured non-contact using a 3D profiler, the NV-2200 from NanoSystems, Inc., and the 3D roughness was measured.

[0072] c. Average particle size of the primary particle layer

[0073] Immediately after forming a primary particle layer on the surface of the raw foil in the examples and comparative examples, a FE-SEM image was taken of the surface using a scanning electron microscope. The particle size was measured for 100 copper particles within a 5 μm × 5 μm area, and their average values ​​were calculated.

[0074] d. Average particle size of the secondary particle layer

[0075] Immediately after forming the secondary particle layer in the examples and comparative examples, a FE-SEM image was taken of the surface using a scanning electron microscope. The particle size was measured for 50 secondary particles within a 5 μm × 5 μm area, and the average value was calculated to determine the average particle size.

[0076] e. Adhesive strength (unit: kgf / cm)

[0077] Copper foil test pieces were prepared with a width of 10 mm and pressed onto Teflon® resin at 380°C to prepare the samples. The adhesive strength was confirmed using the 90° peel method in accordance with JIS C64718.1. The insulator used was a 50 μm thick Teflon® product with the product name EA-2000 (manufactured by AGC Inc.).

[0078] f. Particle quantity of the secondary particle layer

[0079] A 10cm x 10cm sample of surface-treated copper foil was prepared, immersed in a hydrochloric acid hydrolysate solution to dissolve a 1μm thick layer of the surface, and then the raw solution was analyzed by ICP analysis to determine the amount of particles in the secondary particle layer (Zn).

[0080] g. High-temperature degradation rate of adhesive strength

[0081] For samples where adhesive strength was confirmed by high-temperature pressing with Teflon® resin, the adhesive strength was measured using the method described above and set as the reference value. Subsequently, the samples were kept in an oven at 177°C for 10 days, and the adhesive strength was measured again. The rate of change from the reference value was defined as the high-temperature degradation rate (%) of adhesive strength.

[0082] Table 1 below lists the measured physical properties.

[0083] [Table 1]

[0084] Figures 3A and 3B are electron microscope images of the surfaces of the surface-treated copper foils produced in Example 1 and Comparative Example 2, respectively. Referring to Figure 3, it can be seen that in Example 1, a secondary particle layer with a particle aggregate structure, composed of coarser particles than the underlying primary particle layer, is formed on the surface. However, in Comparative Example 2, it can be seen that the particle aggregate structure is not developed. This is thought to be because the Zn supplied as the secondary particle source was uniformly deposited on the particle surface of the primary particle layer rather than forming a separate layer. This phenomenon was also observed in Comparative Example 3, and it can be seen that this resulted in a very low degradation rate. On the other hand, although a particle aggregate structure was formed in Comparative Example 1, it was found that the amount of particles in the secondary particle layer was lower than in Examples 1 and 2, and it is thought that this factor led to a rapid increase in the degradation rate.

[0085] Preferred embodiments of the present invention have been described in detail above. A person with ordinary skill in the art to which the present invention belongs will understand that various modifications are possible to the above embodiments without departing from the scope of the present invention. Therefore, the scope of the rights of the present invention should not be defined by the embodiments described, but by the claims and equivalents described below. [Industrial applicability]

[0086] The present invention is applicable to electrolytic copper foil, copper foil laminates, and printed circuit boards.

Claims

1. A surface-treated copper foil having a surface treatment layer comprising a primary particle layer containing Cu or Cu alloy particles formed on at least one surface of the copper foil, and a secondary particle layer containing Zn particles formed on the primary particle layer, The surface-treated copper foil is characterized in that the primary particle layer covers the entire surface area of ​​the copper foil, and the secondary particle layer consists of particle aggregates formed by the aggregation of a plurality of Zn particles, and the particle aggregates are discontinuously distributed on the primary particle layer.

2. The surface treatment layer of the surface-treated copper foil has a surface roughness (R ｚ The surface-treated copper foil according to claim 1, characterized in that the thickness of the surface is 1.0 μm or less.

3. The surface-treated copper foil according to claim 1, characterized in that the particle aggregates are distributed on average at a rate of two or more per 5 μm × 5 μm area of ​​the surface-treated copper foil.

4. The surface-treated copper foil according to claim 1, characterized in that the particle aggregates are distributed in an area of ​​5 μm × 5 μm of the surface-treated copper foil in a number of 15 or fewer particles.

5. The surface-treated copper foil according to claim 1, characterized in that the particle size of the secondary particle layer is larger than the particle size of the primary particle layer.

6. The surface-treated copper foil according to claim 5, characterized in that the average particle size of the primary particle layer is less than 100 nm, and the average particle aggregate size of the secondary particle layer is 0.5 μm to 2.0 μm.

7. The Zn concentration of the surface treatment layer is 2000 μg / dm ２ The surface-treated copper foil according to claim 1, characterized in that it is as described above.

8. The Zn concentration of the surface treatment layer is 3500 μg / dm ２ The surface-treated copper foil according to claim 1, characterized in that it is as follows.

9. The surface-treated copper foil according to claim 1, further comprising a rust-preventive layer on the secondary particle layer.

10. The surface-treated copper foil according to claim 9, characterized in that the rust-preventive layer contains chromium.

11. The surface-treated copper foil according to claim 1, characterized in that the copper base foil is an electrolytic copper foil.

12. A copper foil laminate in which a surface-treated copper foil according to any one of claims 1 to 11 is laminated on a resin substrate.

13. The copper foil laminate according to claim 12, characterized in that the resin substrate is a PTFE substrate.

14. The copper foil laminate according to claim 12, characterized in that the high-temperature degradation rate of adhesive strength is less than 10%.

15. A printed circuit board formed using the copper foil laminate described in claim 12.

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