Ultra-low profile metal foil with high peel strength and circuit board

Abstract

The invention discloses an ultra-low profile metal foil with high peel strength, at least one side surface of the metal foil is provided with a surface treatment layer, the surface treatment layer at least comprises a first coupling agent, the first coupling agent is gamma-aminopropyltriethoxysilane, and the thickness of the surface treatment layer is 0.1-1 micron. A surface treatment layer with the thickness of 0.1-1 micron is arranged on at least one side surface of a metal foil, and the surface treatment layer at least comprises gamma-aminopropyltriethoxysilane. Silanol is generated after gamma-aminopropyltriethoxysilane is hydrolyzed, the silanol reacts with the metal foil to form Si-O-Cu covalent bonds, amino reacts with active groups of resin, the bonding performance between the metal foil and a base material is greatly improved, the bonding performance between the metal foil and the base material is further improved by adopting a composite coupling agent, and the bonding performance between the metal foil and the base material is improved. The metal foil has a low-profile surface, and meanwhile, the metal foil and the base material can be ensured to have relatively good bonding performance, so that the high-frequency transmission requirement is met, and the reliability of a circuit is improved.

Description

Technical Field

[0001] This invention relates to the field of metal foil technology, and in particular to a metal foil and a circuit board. Background Technology

[0002] With the rapid development of global information technology towards digitalization and networking, there is a growing demand for ultra-large capacity information transmission and high-speed, ultra-high density information processing. This undoubtedly places more stringent requirements on the performance of electrolytic metal foil. As a key material, high-frequency transmission copper foil is significantly affected by the stability and reliability of signal transmission in high-frequency signal transmission scenarios.

[0003] To ensure high-frequency transmission performance, metal foils require ultra-low profile surfaces. However, existing technologies that maintain ultra-low profile surfaces reduce the contact area between the metal foil and the substrate. Van der Waals forces and other intermolecular forces cannot compensate for the lack of mechanical interlocking forces, resulting in weak adhesion between the metal foil and the substrate. This leads to delamination and peeling during thermal shocks, such as PCB soldering reflow processes with temperature cycling at 260℃ for 10 seconds, or mechanical stresses, such as drilling and punching, ultimately rendering the circuit board unusable. To address these technical issues, it is necessary to ensure that the metal foil has a low profile surface while maintaining good adhesion between the metal foil and the substrate. Summary of the Invention

[0004] Based on this, the main objective of this application is to provide an ultra-low profile metal foil and circuit board with high peel strength, which can meet the requirements of high frequency transmission, while ensuring that the metal foil and the substrate have good adhesion performance, thereby improving the reliability of the circuit.

[0005] To achieve the above objectives, the first aspect of the present invention provides an ultra-low profile metal foil with high peel strength, wherein at least one side of the metal foil is provided with a surface treatment layer, the surface treatment layer contains at least a first coupling agent, the first coupling agent being γ-aminopropyltriethoxysilane, and the thickness of the surface treatment layer is 0.1 micrometer to 1 micrometer.

[0006] As a preferred embodiment, the surface treatment layer includes a second silane coupling agent and a third silane coupling agent, wherein the second silane coupling agent is 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane and the third silane coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0007] As a preferred embodiment, the content ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane is 1:(1.1~2).

[0008] As a preferred embodiment, the content ratio of γ-aminopropyltriethoxysilane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:(0.5~0.9).

[0009] As a preferred embodiment, the surface treatment layer includes a titanate coupling agent, wherein the titanate coupling agent accounts for 0.1 to 0.5 wt% of the surface treatment layer by mass.

[0010] As a preferred embodiment, the thickness of the surface treatment layer is 0.1 micrometer to 0.5 micrometer.

[0011] As a preferred embodiment, the metal foil has a plurality of protrusions on the side near the surface treatment layer, the number of protrusions being greater than or equal to 400,000 per m. 2 .

[0012] As a preferred embodiment, the surface roughness Rz of the metal foil on the side closest to the surface treatment layer is less than or equal to 2.0 micrometers.

[0013] As a preferred embodiment, a protective layer is provided between the metal foil and the surface treatment layer.

[0014] To achieve the above objectives, a second aspect of the present invention also provides a circuit board comprising the metal foil described in any of the above embodiments.

[0015] Compared to existing technologies, the advantages of this invention are as follows: By providing a surface treatment layer with a thickness of 0.1 micrometers to 1 micrometer on at least one side of the metal foil, the surface treatment layer contains at least γ-aminopropyltriethoxysilane. The silanol generated after the hydrolysis of γ-aminopropyltriethoxysilane reacts with the metal foil to form Si-O-Cu covalent bonds, and the amino groups react with the active groups of the resin, significantly improving the adhesion between the metal foil and the substrate. The use of a composite coupling agent further enhances the adhesion between the metal foil and the substrate, resulting in a low-profile surface on the metal foil. Simultaneously, it ensures good adhesion between the metal foil and the substrate, thereby meeting the requirements of high-frequency transmission and improving the reliability of the circuit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings are only for illustrating preferred embodiments and are not intended to limit this application. Throughout the drawings, the same reference numerals denote the same parts. In the drawings:

[0017] Figure 1 This is a schematic diagram of the structure of the first type of ultra-low profile metal foil with high peel strength provided in the embodiments of the present invention;

[0018] Figure 2 This is a schematic diagram of the structure of the second type of ultra-low profile metal foil with high peel strength provided in the embodiments of the present invention;

[0019] Figure 3 This is a schematic diagram of the structure of the third type of ultra-low profile metal foil with high peel strength provided in the embodiments of the present invention.

[0020] Among them, 1. metal foil; 2. surface treatment layer; 3. protective layer; 11. protrusion. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In the description of the specification and claims, it should be understood that the terms "upper", "lower", "left", "right", "front", "rear", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present invention, and do not indicate or imply that the device or component referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the embodiments of the present invention.

[0023] Furthermore, the terms "first," "second," etc., used in the specification and claims are used only to distinguish the description of the same technical features and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated, nor necessarily the order of description or chronological sequence. Where appropriate, the terms are interchangeable. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature.

[0024] Please see Figure 1 , Figure 1This is a schematic diagram of the structure of a high peel strength ultra-low profile metal foil according to an embodiment of the present invention. The embodiment of the present invention provides a metal foil 1, wherein at least one side of the metal foil is provided with a surface treatment layer 2, the surface treatment layer 2 comprising at least a first coupling agent, the first coupling agent being γ-aminopropyltriethoxysilane, and the thickness of the surface treatment layer 2 being 0.1 micrometers to 1 micrometer. The silanol generated after the hydrolysis of γ-aminopropyltriethoxysilane reacts with the metal foil to form Si-O-Cu covalent bonds, and the amino groups react with the active groups of the resin, significantly improving the adhesion performance between the metal foil and the substrate. The use of a composite coupling agent further enhances the adhesion performance between the metal foil and the substrate, resulting in a low profile surface for the metal foil. Simultaneously, it ensures good adhesion performance between the metal foil and the substrate, thereby meeting the requirements of high-frequency transmission and improving the reliability of the circuit.

[0025] Preferably, the thickness of the surface treatment layer 2 is 0.1 micrometers to 0.5 micrometers.

[0026] It is worth noting that before forming the surface treatment layer 2 on the surface of metal foil 1, the side of metal foil 1 closest to the surface treatment layer 2 needs to be cleaned to remove grease, oxides, and contaminants, and to enrich its surface with hydroxyl groups (-OH). This is a prerequisite for the effective bonding of the silane coupling agent γ-aminopropyltriethoxysilane. Cleaning methods include cleaning the metal foil in an ultrasonic cleaner with organic solvents for several minutes to remove organic contaminants and fingerprints. After removal, rinse with plenty of deionized water. Alternatively, micro-etching with an acidic or alkaline etching solution can be used. Then, thoroughly rinse the surface of the metal foil with plenty of flowing deionized water to ensure that there is no acid or salt residue, preventing subsequent contamination and inactivation of the γ-aminopropyltriethoxysilane solution. Dry with high-purity nitrogen or air dry in a clean environment (such as a glove box). Avoid using a regular oven to dry, as this may cause re-oxidation of the surface.

[0027] Furthermore, the method for forming the surface treatment layer 2 on the surface of the metal foil 1 includes one or a combination of two or more of the following methods: immersion, spin coating, or spray coating. Immersion involves completely immersing the pre-treated and dried metal foil 1 in a prepared γ-aminopropyltriethoxysilane solution. The immersion time is typically between 2 and 30 minutes; too short a time may result in incomplete coverage, while too long a time may lead to multilayer adsorption or self-polymerization. A preferred time is 5-15 minutes. Spin coating involves fixing the metal foil 1 on a spin coater, adding the γ-aminopropyltriethoxysilane solution dropwise onto the surface of the metal foil 1, starting the spin coater, and setting an appropriate rotation speed and time to allow for uniform spreading and solvent evaporation. Spray coating involves using a spray gun to uniformly spray the γ-aminopropyltriethoxysilane solution onto the surface of the metal foil 1. This method requires careful control of the spray volume, distance, and uniformity, and is suitable for large-area continuous processing, but the uniformity and thickness control are slightly worse than with immersion.

[0028] It should be noted that, in order to promote the condensation reaction between silanol and the hydroxyl groups on the surface of the metal foil (forming Si-O-Cu bonds), and simultaneously cause intermolecular condensation between adjacent silanol molecules (forming a Si-O-Si network), thereby improving the stability of the film and the adhesion to the substrate, the metal foil 1 is placed in an oven for heating and curing. Preferably, curing is carried out in an inert atmosphere (nitrogen or argon) or a vacuum environment.

[0029] Furthermore, the surface treatment layer includes a second coupling agent and a third coupling agent. The second coupling agent is 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and the third coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane. γ-aminopropyltriethoxysilane, 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and γ-(2,3-epoxypropoxy)propyltrimethoxysilane are used in combination. The primary amine group in γ-aminopropyltriethoxysilane undergoes a ring-opening reaction with the methyl-containing epoxy silane and the epoxy groups in γ-(2,3-epoxypropoxy)propyltrimethoxysilane to form a cross-linked silane network. This cross-linked network provides a stronger and more robust "bridge" between inorganic and organic materials. This network structure is denser and more stable than a single layer or linear structure formed by a single silane, which can significantly improve the interface strength, ensure good adhesion between the metal foil and the substrate, and thus meet the requirements of high-frequency transmission and improve the reliability of the line.

[0030] Optionally, the content ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane is 1:(1.1~2). The primary amine group on the aminopropyl silane in γ-aminopropyltriethoxysilane has high reactivity and can undergo ring-opening addition reactions with the epoxy groups on the epoxy silane to form a cross-linked network, creating a "pre-coupling" or "molecular bridge" structure between inorganic and organic materials. The siloxane end of the aminopropyl silane is anchored to the inorganic surface, while the epoxy end of the epoxy silane interacts or reacts with the organic resin. The intermediate amine-epoxy link provides a strong chemical bond, significantly improving the adhesion between the metal foil and the substrate. By limiting the content ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane to the aforementioned range, the excess epoxy groups help consume free primary amine groups, preventing the free primary amine groups from being too basic and incompatible with the resin, thus reducing the adhesion between the metal foil and the substrate. Simultaneously, the excess epoxy groups can participate in other reactions, such as reactions with functional groups of the resin matrix, self-hydrolysis condensation, or reactions with silanol groups, contributing to the formation of a denser, more cross-linked hybrid network structure. On the other hand, a too-small content ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane prevents a severe excess of epoxy groups, which could affect the strength of the cross-linked network structure and consequently reduce the interfacial strength with other materials. On the other hand, a high ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane would not generate a large number of free primary amine groups, leading to strong basicity of the primary amine groups, incompatibility with the resin, and consequently reduced interfacial bonding with other materials. Therefore, limiting the ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane to the aforementioned range maximizes the synergistic coupling effect of the two silanes, constructing a strong "molecular bridge" between inorganic and organic materials, and improving the bonding force between the metal foil and the substrate. Optionally, the ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane can be any one of the values ​​or a range of any two values ​​from 1:1.1, 1:1.3, 1:1.5, 1:1.7, 1:1.9, and 1:2.

[0031] Furthermore, the content ratio of γ-aminopropyltriethoxysilane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:(0.5~0.9). The methoxy group in γ-(2,3-epoxypropoxy)propyltrimethoxysilane hydrolyzes extremely rapidly, quickly condensing on the metal foil surface to form a dense siloxane film that blocks water vapor permeation. The primary amine group on the aminopropyl silane in γ-aminopropyltriethoxysilane has high reactivity and can undergo ring-opening addition reactions with the epoxy groups on the epoxy silane to form a cross-linked network, creating a "pre-coupling" or "molecular bridge" structure between inorganic and organic substances. However, in a humid environment, metal ions diffuse into the resin, easily leading to interfacial failure. By limiting the content ratio of γ-aminopropyltriethoxysilane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane to 1:(0.5~0.9), the excess free primary amine groups capture free metal ions, forming a chelate structure with excellent thermal stability, blocking ion migration channels, and ensuring the reliability of the circuit quality. This results in high adhesion between the metal foil and the substrate, while preventing metal ion migration, meeting the requirements of high-frequency and high-speed circuits.

[0032] It is worth noting that the surface treatment layer 2 also includes a titanate coupling agent, which accounts for 0.1~0.5 wt% of the surface treatment layer by mass. The high peel strength ultra-low profile metal foil of this embodiment can be applied in the PCB field, where the surface treatment layer 2 of the metal foil is laminated with a substrate. The substrate includes a prepreg of the circuit board, which is composed of resin and filler. By adding the titanate coupling agent to the surface treatment layer 2, it reacts with the -OH or -COOH groups on the surface of the filler in the prepreg to form chemical bonds. Simultaneously, the ester groups and carboxyl groups in the titanate coupling agent undergo cross-linking reactions, further increasing the bonding force between the metal foil and the prepreg. The titanate coupling agent molecules can strengthen the interaction between the metal foil surface and the substrate material through intermolecular van der Waals forces and hydrogen bonds. Van der Waals forces can generate a weak attractive force between the coupling agent molecules and the metal foil surface and substrate material molecules, while hydrogen bonds can further enhance this interaction, thereby improving the bonding performance between materials. By limiting the titanate coupling agent to a mass percentage of 0.1–0.5 wt% in the surface treatment layer, sufficient coupling agent molecules are adsorbed onto the metal foil surface, undergoing effective coordination reactions with metal atoms, thereby enhancing the chemical bonding between the metal foil surface and the substrate. Simultaneously, this ensures the titanate coupling agent is uniformly dispersed on the metal foil surface, allowing subsequent coating materials to adhere more evenly, helping to avoid problems such as uneven coating and bubbles, and improving the product's appearance quality and performance consistency.

[0033] See Figure 2 , Figure 2This is a schematic diagram of another high peel strength ultra-low profile metal foil according to an embodiment of the present invention. The metal foil 1 has a plurality of protrusions on one side near the surface treatment layer 2, the number of protrusions being greater than or equal to 400,000 per m. 2 By providing protrusions 11 on one side of the metal foil 1 near the surface treatment layer 2, a mechanical riveting effect is formed with the substrate. The protrusions 11 increase the contact area between the metal foil and the substrate, improving their bonding strength. Simultaneously, the protrusions 11 also increase the contact area between the surface treatment layer and the substrate, promoting the formation of chemical bonds between the surface treatment layer and the metal foil and substrate, resulting in a stronger interfacial bond. Preferably, the number of protrusions 11 is greater than or equal to 400,000 per m. 2 .

[0034] It should be noted that the protrusion 11 in this embodiment of the invention is formed by one or a combination of at least two of the following processes: electrolytic deposition, roll embossing, or chemical etching. Electrolytic method: Periodic protrusions are formed on the cathode surface by adjusting the pulse current parameters (frequency, duty cycle). Embossing method: Regular protrusions are pressed onto the surface of the metal foil using a microstructured roller. Chemical etching method: Protrusions are formed by etching the metal foil with chemical solutions through a subtractive process.

[0035] Furthermore, the surface roughness Rz of the side of the metal foil closest to the surface treatment layer is less than or equal to 2.0 micrometers. During high-frequency, high-speed signal transmission, the skin effect causes current to concentrate in a very thin layer on the surface of the metal foil. Signal transmission essentially follows the contour curve of the metal foil, and its transmission distance is closely related to the surface roughness Rz. The larger the surface roughness Rz of the metal foil, the longer the signal transmission distance, resulting in a slower signal transmission speed and increased transmission loss. To reduce signal transmission loss in high-frequency circuits, low-profile, smooth-surface metal foils are required. When the surface roughness Rz of the metal foil closest to the surface treatment layer is ≤ 2.0 micrometers, compared to metal foils with higher roughness, the current transmission path on the metal foil surface is smoother, reducing current path detours and scattering caused by surface undulations. This reduces the additional resistance loss caused by the skin effect, enabling more efficient signal transmission.

[0036] In this embodiment of the invention, the metal foil is used to fabricate the circuit. The metal foil is selected from any one or a combination of at least two of nickel, chromium, copper, silver, gold, zinc, iron, titanium, or aluminum. The thickness of the metal foil is 1 to 35 micrometers.

[0037] It should be noted that when the thickness of metal foil 1 is too thin to be directly processed and used, a carrier layer is required. Therefore, the carrier layer serves a supporting function, carrying the metal foil. The thickness of the carrier layer is 8~28μm. The carrier layer can be made of at least one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver, and gold.

[0038] See Figure 3 , Figure 3 This is a schematic diagram of another high peel strength ultra-low profile metal foil according to an embodiment of the present invention. A protective layer 3 is provided between the metal foil 1 and the surface treatment layer 2. The protective layer 3 serves to prevent oxidation, thus preventing the metal foil 1 from oxidizing and affecting its quality. It is understood that without the protective layer 3, the metal foil 1 is easily oxidized under conditions such as temperature, moisture, and corrosive gases, leading to abnormal circuit processing. Therefore, in this embodiment of the present invention, a protective layer 3 is provided between the metal foil 1 and the surface treatment layer 2, which can prevent the oxidation reaction between the metal foil 1 and substances such as temperature, moisture, and corrosive gases, thereby improving the quality and performance of the metal foil.

[0039] Embodiments of the present invention also provide a circuit board, which includes the metal foil of any embodiment of the present invention.

[0040] Compared to existing technologies, the advantages of this invention are as follows: By providing a surface treatment layer with a thickness of 0.1 micrometers to 1 micrometer on at least one side of the metal foil, the surface treatment layer contains at least γ-aminopropyltriethoxysilane. The silanol generated after the hydrolysis of γ-aminopropyltriethoxysilane reacts with the metal foil to form Si-O-Cu covalent bonds, and the amino groups react with the active groups of the resin, significantly improving the adhesion between the metal foil and the substrate. The use of a composite coupling agent further enhances the adhesion between the metal foil and the substrate, resulting in a low-profile surface on the metal foil. Simultaneously, it ensures good adhesion between the metal foil and the substrate, thereby meeting the requirements of high-frequency transmission and improving the reliability of the circuit.

[0041] To demonstrate the beneficial effects of the metal foil and circuit board provided in the embodiments of the present invention, the following description is provided in conjunction with several embodiments and comparative examples.

[0042] Example 1:

[0043] A high peel strength ultra-low profile metal foil, wherein at least one side of the metal foil is provided with a surface treatment layer, the surface treatment layer having a thickness of 0.5 micrometers, the surface treatment layer containing at least a first coupling agent, the first silane coupling agent being γ-aminopropyltriethoxysilane, the metal foil having a thickness of 12 μm, and the surface roughness Rz of the side of the metal foil near the surface treatment layer having a thickness of 1.5 micrometers.

[0044] Example 2:

[0045] The high peel strength ultra-low profile metal foil of this embodiment is the same as that of Embodiment 1, except that the surface treatment layer further includes a second coupling agent and a third coupling agent. The second coupling agent is 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and the third coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane. The content ratio of γ-aminopropyltriethoxysilane to 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane is 1:1.5.

[0046] Example 3:

[0047] The high peel strength ultra-low profile metal foil of this embodiment is the same as that of Embodiment 1, except that the surface treatment layer further includes a second coupling agent and a third coupling agent. The second coupling agent is 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane, and the third coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane. The content ratio of γ-aminopropyltriethoxysilane to γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:0.7.

[0048] Example 4:

[0049] The high peel strength ultra-low profile metal foil of this embodiment is the same as that of Embodiment 1, except that the surface treatment layer includes a titanate coupling agent, and the titanate coupling agent accounts for 0.5 wt% of the surface treatment layer by mass.

[0050] Example 5:

[0051] The high peel strength ultra-low profile metal foil in this embodiment is the same as that in Embodiment 1, except that: the metal foil has a plurality of protrusions on the side near the surface treatment layer, and the number of protrusions is greater than or equal to 400,000 per m. 2 .

[0052] Comparative Example 1:

[0053] A metal foil with a surface roughness Rz of 1.5 micrometers and a thickness of 12 micrometers.

[0054] Comparative Example 2:

[0055] The metal foil in this comparative example is the same as that in Comparative Example 1, except that the surface roughness Rz of the metal foil is 4 micrometers.

[0056] Comparative Example 3:

[0057] The metal foil in this comparative example is the same as that in Comparative Example 1, except that the rough surface of the metal foil is provided with a surface treatment layer, which is a zinc-nickel alloy and has a thickness of 0.1 micrometers.

[0058] The metal foils of Examples 1-5 and Comparative Examples 1-3 were fabricated using circuit board manufacturing processes, and the circuit detachment and high-frequency transmission performance were tested and evaluated. The evaluation results are shown in Table 1.

[0059] Table 1. Peel strength and high-frequency performance of metal foils from Examples 1-5 and Comparative Examples 1-3

[0060]

[0061] As can be seen from Table 1, the high peel strength ultra-low profile metal foil of the present invention can not only ensure excellent high-frequency transmission performance, but also has high peel strength between the metal foil and the substrate, so that no abnormal wire splay will occur during the fabrication of the circuit, which effectively improves the quality and reliability of the circuit.

[0062] In summary, by providing a surface treatment layer with a thickness of 0.1-1 micrometer on at least one side of the metal foil, and the surface treatment layer containing at least γ-aminopropyltriethoxysilane, the adhesion between the metal foil and the substrate is significantly improved by utilizing the silanol generated after the hydrolysis of γ-aminopropyltriethoxysilane, which reacts with the metal foil to form Si-O-Cu covalent bonds, and the reaction of amino groups with the active groups of the resin. Furthermore, the use of a composite coupling agent further enhances the adhesion between the metal foil and the substrate, resulting in a low-profile surface on the metal foil. Simultaneously, it ensures good adhesion between the metal foil and the substrate, thereby meeting the requirements of high-frequency transmission and improving the reliability of the circuit.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0064] The embodiments described above are merely illustrative of several implementation methods of this application, intended to facilitate a detailed understanding of the technical solutions of this application, but should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the scope of protection of this application. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided in this application through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this patent application should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. A high peel strength ultra-low profile metal foil, characterized in that, The metal foil has a surface treatment layer on at least one side, the surface treatment layer contains at least a first coupling agent, the first coupling agent is γ-aminopropyltriethoxysilane, and the thickness of the surface treatment layer is 0.1 micrometer to 1 micrometer.

2. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, The surface treatment layer includes a second coupling agent and a third coupling agent, wherein the second coupling agent is 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane and the third coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

3. The high peel strength ultra-low profile metal foil as described in claim 2, characterized in that, The content ratio of the γ-aminopropyltriethoxysilane to the 3-(2,3-epoxypropoxy)propylmethyldimethoxysilane is 1:(1.1~2).

4. The high peel strength ultra-low profile metal foil as described in claim 2, characterized in that, The content ratio of the γ-aminopropyltriethoxysilane to the γ-(2,3-epoxypropoxy)propyltrimethoxysilane is 1:(0.5~0.9).

5. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, The surface treatment layer includes a titanate coupling agent, and the titanate coupling agent accounts for 0.1~0.5 wt% of the surface treatment layer by mass.

6. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, The thickness of the surface treatment layer is 0.1 micrometer to 0.5 micrometer.

7. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, The metal foil has a plurality of protrusions on one side near the surface treatment layer, the number of protrusions being greater than or equal to 400,000 per m. 2 .

8. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, The surface roughness Rz of the metal foil on the side closest to the surface treatment layer is less than or equal to 2.0 micrometers.

9. The high peel strength ultra-low profile metal foil as described in claim 1, characterized in that, A protective layer is provided between the metal foil and the surface treatment layer.

10. A circuit board, characterized in that, The circuit board contains the metal foil as described in claims 1-9.

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