Metal foil, circuit board, and method for manufacturing a circuit board

Abstract

The present invention relates to the technical field of metal foil, and discloses a metal foil including a conductive layer and a carrier layer, the conductive layer and the carrier layer being laminated, the conductive layer being used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the carrier layer and the conductive layer are separated by a first etching solution, and the roughness Rz of the surface of the carrier layer close to the conductive layer is 2 microns or less. When a circuit board is manufactured using the metal foil, the surface of the conductive circuit and the surface of the board after removing the carrier layer are basically flush with each other, and the surface roughness of the conductive circuit is small, meeting the product demands with high dimensional accuracy. In accordance with this, the present invention also provides a circuit board and a method for manufacturing the circuit board.

Description

Technical Field

[0001] The present invention relates to the technical field of metal foils, and particularly to metal foils, circuit boards, and methods for manufacturing circuit boards.

Background Art

[0002] An embedded circuit board is a circuit board in which a conductive circuit is embedded within the circuit board. As shown in FIG. 1, in an application scenario where the sensitivity of the circuit is required, in order to ensure that the conductive circuit and other devices are in reliable contact and thereby ensure stable signal transmission, it is necessary to ensure that the surface of the conductive circuit is flat and that the surface of the conductive circuit is substantially flush with the surface of the substrate or slightly protrudes from the surface of the substrate. In addition, for products with high requirements for dimensional accuracy, it is necessary to keep the step between the surface of the conductive circuit and the surface of the substrate within a certain range.

[0003] Currently, in order to ensure that the step between the surface of the conductive circuit and the surface of the substrate is within a certain range, the main process flow of the conventional method for manufacturing circuit boards is as follows. (1) First, a peelable metal foil is manufactured. The metal foil includes a carrier layer and a conductive layer provided in a stacked manner. (2) A film is attached to the conductive layer, and exposure and development operations are performed, where the masked area by the mask pattern is the non-conductive circuit area and the unmasked area by the mask pattern is the conductive circuit area, to obtain a mask pattern. (3) Electroplating is performed to thicken the conductive circuit area. (4) The surface of the metal foil on which the conductive circuit is formed is pressed onto the substrate, and the carrier layer is removed by peeling (i.e., the carrier layer is torn by an external force). (5) The conductive layer is etched using an etching solution to remove the conductive layer in the peelable metal foil and form a conductive circuit. (6) Surface treatment is performed on the conductive circuit so that the surface of the conductive circuit is substantially flush with the surface of the substrate or is a certain height higher than the surface of the substrate.

[0004] In actual applications, when the conductive layer is etched using an etching solution in step (5) to remove the conductive layer from the peelable metal foil, since the material of the thickly formed conductive circuit and the material of the conductive layer on the peelable metal foil are the same, the etching solution can not only etch the conductive layer but also the thickly formed conductive circuit. Furthermore, in order to avoid the phenomenon of minute short circuits due to incomplete etching of the conductive layer at the bottom of the substrate and to ensure that the conductive layer at the bottom of the substrate is cleanly etched, over-etching is often performed during the etching process of the conductive layer, and as shown in Figures 1 and 2, after etching is complete, the conductive circuit becomes recessed into the substrate. In actual production, the recess of the conductive circuit in the substrate in the height direction is greater than 0.5 microns. This makes it difficult to realize the process in step (6), for example, to make the conductive circuit flush with the substrate or protrude from the substrate by gold plating or nickel plating. At least in conventional processes, it is difficult to perform surface treatment under such high steps so that the surface-treated conductive circuit becomes flush with the substrate or protrudes from the substrate. Furthermore, the recessed conductive circuits within the substrate significantly increase the raw material and processing costs for surface treatment. Moreover, because precise control of the etching area cannot be achieved during the etching process, the degree of over-etching does not match between different parts of the conductive circuit and the substrate, resulting in significant differences in surface roughness. Consequently, the resulting circuit board fails to meet the demands for products with high dimensional accuracy requirements. [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] The object of the embodiment of the present invention is to provide a metal foil, a circuit board, and a method for manufacturing a circuit board that, when manufacturing a circuit board with metal foil, have a surface on the conductive circuit from which the support layer has been removed and the surface of the substrate that are essentially flush, and have a small surface roughness on the conductive circuit, thereby meeting the demand for a product with high dimensional accuracy. [Means for solving the problem]

[0006] An embodiment of the present invention to solve the above problems provides a metal foil comprising a conductive layer and a support layer, wherein the conductive layer and the support layer are laminated together, the conductive layer is used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the support layer and the conductive layer are separated by a first etching solution, the conductive layer has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer near the conductive layer is 2 microns or less.

[0007] In a preferred embodiment, the surface roughness Rz of the support layer near the conductive layer is 1 micron or less.

[0008] In a preferred embodiment, the support layer includes a transition layer, the transition layer and the conductive layer are laminated together, and when manufacturing a circuit board using the metal foil, the transition layer is etched with the first etching solution so that the support layer and the conductive layer are separated.

[0009] In a preferred embodiment, the transition layer has corrosion resistance to a second etching solution that can etch the conductive layer.

[0010] In a preferred embodiment, the conductive layer is a copper layer, and the transition layer contains at least one of the elements nickel, chromium, manganese, iron, and cobalt.

[0011] In a preferred embodiment, the thickness of the support layer is 8 to 105 microns.

[0012] In a preferred embodiment, the supporting layer further includes a carrier layer, and the transition layer is provided between the carrier layer and the conductive layer.

[0013] In a preferred embodiment, the material of the carrier layer is at least one selected from metals and nonmetals.

[0014] In a preferred embodiment, when a circuit board is manufactured using the metal foil, the carrier layer is removed by a non-peeling method.

[0015] In a preferred embodiment, when a circuit board is manufactured using the metal foil, the carrier layer is removed by peeling.

[0016] In a preferred embodiment, the material of the transition layer is corrosion-resistant to the third etching solution, and when manufacturing a circuit board using the metal foil, the carrier layer is etched with the third etching solution.

[0017] In a preferred embodiment, the support layer further includes a release layer provided between the carrier layer and the transition layer.

[0018] In a preferred embodiment, the sum of the thicknesses of the conductive layer and the transition layer is 0.2 microns or more.

[0019] Accordingly, embodiments of the present invention further provide circuit boards manufactured from a substrate and the metal foil.

[0020] Accordingly, an embodiment of the present invention is a method for manufacturing a circuit board using the metal foil, The steps include: manufacturing a circuit on the conductive layer to obtain a conductive circuit, The steps include connecting the conductive circuit and the substrate, The present invention further provides a method for manufacturing a circuit board, which includes the step of removing the support layer.

[0021] In a preferred embodiment, after the step of removing the support layer, The process further includes the step of performing a surface treatment on the conductive circuit so that the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step difference range.

[0022] In a preferred embodiment, the step of manufacturing a circuit on the conductive layer to obtain a conductive circuit specifically includes: Performing film pasting, exposure, and development operations on the conductive layer where the unmasked area by the mask pattern is a non-conductive circuit area to obtain a mask pattern; Etching the non-conductive circuit area using a second etching solution; Removing the mask pattern to obtain a conductive circuit, including:

[0023] In a preferred embodiment, for manufacturing a conductive circuit on the conductive layer, the step of obtaining a conductive circuit specifically includes: Performing film pasting, exposure, and development operations on the conductive layer where the unmasked area by the mask pattern is a conductive circuit area to obtain a mask pattern; Thickening the conductive circuit area; Removing the mask pattern; Performing high-speed etching using a second etching solution to remove the unthickened area of the conductive layer to obtain a conductive circuit, including:

[0024] In a preferred embodiment, before the step of performing film pasting, exposure, and development operations on the conductive layer to obtain a mask pattern, Further including the step of thinning the conductive layer.

[0025] In a preferred embodiment, a multilayer circuit board is manufactured using the circuit board.

[0026] Correspondingly, an embodiment of the present invention provides a multilayer circuit board including the circuit board and / or the circuit board manufactured by the manufacturing method of the circuit board.

[0027] Correspondingly, an embodiment of the present invention provides a manufacturing method of a multilayer circuit board including the manufacturing method of the circuit board.

Advantages of the Invention

[0028] Compared to the prior art, the beneficial effects of the embodiment of the present invention are as follows. Specifically, the embodiment of the present invention provides a metal foil comprising a conductive layer and a support layer, wherein the conductive layer and the support layer are laminated together, the conductive layer is used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the support layer and the conductive layer are separated by a first etching solution, the conductive layer has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer near the conductive layer is 2 microns or less. In the embodiment of the present invention, the surface roughness of the support layer near the conductive layer in the metal foil is 2 microns or less. As a result, the surface of the conductive layer near the support layer also has low roughness. When a conductive circuit is formed with the metal foil according to the embodiment of the present invention and a circuit board is manufactured using the metal foil, the support layer and the conductive layer are separated with a first etching solution. Since the conductive layer has corrosion resistance to the first etching solution, after separating the support layer and the conductive layer with the first etching solution, the surface of the finally formed conductive circuit basically maintains the low surface roughness of the original conductive layer, making it possible to obtain a conductive circuit with a flat surface. Furthermore, after removing the support layer, it is ensured that the surface of the conductive circuit and the surface of the substrate are basically flush. This makes it easier to suppress the step difference between the surface of the conductive circuit and the surface of the substrate, and furthermore, it is possible to meet the demand for products with high dimensional accuracy requirements. Accordingly, the embodiment of the present invention further provides a circuit board and a method for manufacturing a circuit board. [Brief explanation of the drawing]

[0029] [Figure 1] This is a schematic diagram showing a structure in which the surface of the conductive circuit is recessed into the surface of the substrate when manufacturing a circuit board using conventional peelable metal foil. [Figure 2] This is a schematic diagram of the structure of a circuit board manufactured using conventional peelable metal foil. [Figure 3] This is a schematic diagram of the structure of the metal foil according to Example 1 of the present invention. [Figure 4] This is a schematic diagram of the circuit board structure of Embodiment 1 of the present invention. [Figure 5] This is a schematic diagram of the structure of a circuit board with a surface-treated conductive circuit according to Embodiment 1 of the present invention. [Figure 6]This is a schematic diagram of the structure of a metal foil including a carrier layer, a transition layer, and a conductive layer according to Example 2 of the present invention. [Figure 7] This is a schematic diagram of the structure of a metal foil comprising a carrier layer, a release layer, a transition layer, and a conductive layer according to Example 2 of the present invention. [Figure 8] This is a flowchart of the method for manufacturing a circuit board according to Example 1 of the present invention. [Figure 9] This is a flowchart of the first embodiment of step S101 of the method for manufacturing a circuit board according to Example 1 of the present invention. [Figure 10] Flowchart of the second embodiment of step S101 of the method for manufacturing a circuit board according to Example 1 of the present invention, [Modes for carrying out the invention]

[0030] The technical concepts in the embodiments of the present invention will be clearly and completely described below with reference to the drawings of the embodiments of the present invention, and it is clear that the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained based on the embodiments of the present invention without the creative effort of those skilled in the art are all within the scope of the protection of the present invention.

[0031] Example 1 Referring to Figure 3, the metal foil of the embodiment of the present invention includes a conductive layer 1 and a support layer, the conductive layer 1 and the support layer are laminated together, the conductive layer 1 is used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the support layer and the conductive layer 1 are separated by a first etching solution, the conductive layer 1 has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer near the conductive layer is 2 microns or less.

[0032] In the embodiment of the present invention, the metal foil includes a conductive layer 1 and a support layer, the conductive layer 1 and the support layer are laminated together, the conductive layer 1 is used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the support layer and the conductive layer 1 are separated by a first etching solution, the conductive layer 1 has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer closest to the conductive layer is 2 microns or less. In the embodiment of the present invention, the surface roughness of the support layer near the conductive layer in the metal foil is 2 microns or less. As a result, the surface of the conductive layer near the support layer also has low roughness. When a conductive circuit is formed with the metal foil according to the embodiment of the present invention and a circuit board is manufactured with the metal foil, the support layer and the conductive layer 1 are separated with the first etching solution. Since the conductive layer has corrosion resistance to the first etching solution, after separating the support layer and the conductive layer with the first etching solution, the surface of the finally formed conductive circuit basically maintains the low surface roughness of the original conductive layer, making it possible to obtain a conductive circuit with a flat surface. Furthermore, after removing the support layer, it is ensured that the surface of the conductive circuit and the surface of the substrate are basically flush. This makes it easier to suppress the step difference between the surface of the conductive circuit and the surface of the substrate, and furthermore, it is possible to meet the demand for products with high dimensional accuracy requirements.

[0033] Furthermore, the fact that the conductive layer 1 has corrosion resistance to the first etching solution means that the conductive layer 1 is not corroded by the first etching solution, is less susceptible to corrosion, or has a slow etching rate. Because the conductive layer 1 has corrosion resistance to the first etching solution, when manufacturing a circuit board with the metal foil, if the support layer and the conductive layer 1 are separated by the first etching solution, the conductive layer 1 is not corroded by the first etching solution, is less susceptible to corrosion, or has a slow etching rate. In the embodiments of the present invention, by selecting an appropriate etching solution, when the support layer and the conductive layer 1 are separated by the first etching solution, it is possible to ensure that the depth to which the surface of the conductive circuit is recessed into the substrate by the first etching solution is 0.5 microns or less. Furthermore, the specific type of the first etching solution is not particularly limited, and those skilled in the art can select it according to their actual needs as long as the above functions can be achieved.

[0034] In specific implementations, other structures may be provided between the support layer and the conductive layer 1 to realize other functions, for example, an oxidation prevention layer or similar structure may be provided between the support layer and the conductive layer 1. It should be noted that the embodiment of providing other structures between the support layer and the conductive layer 1 is also within the scope of protection of the present invention.

[0035] In the embodiments of the present invention, the surface roughness Rz of the support layer near the conductive layer is 2 microns or less, and may be, for example, 2 microns, 1.5 microns, 1 micron, 0.5 microns, 0.2 microns, 0.1 microns or less, and preferably 1 micron or less. When the surface roughness of the support layer near the conductive layer is within the above range, the surface roughness of the conductive layer near the support layer is also basically within the above range, that is, the surface of the conductive layer near the support layer is flat. Furthermore, in the embodiments of the present invention, the conductive layer has corrosion resistance to the first etching solution that etches and separates the support layer and the conductive layer, so that after separation from the support layer, the surface of the conductive layer near the support layer is less affected by the first etching solution, and the surface of the finally formed conductive circuit basically maintains the surface roughness of the original conductive layer near the support layer, that is, the surface of the conductive circuit is flat.

[0036] Referring to Figure 3, the support layer includes a transition layer 2, and the transition layer 2 and the conductive layer 1 are laminated together. When manufacturing a circuit board using the metal foil, the transition layer 2 is etched with the first etching solution so that the support layer and the conductive layer 1 are separated. In the embodiment of the present invention, the transition layer 2 is etched with the first etching solution to remove the transition layer 2, thereby separating the support layer and the conductive layer 1. Furthermore, the conductive layer 1 has corrosion resistance to the first etching solution, meaning that the first etching solution does not etch the conductive layer 1, etches it with difficulty, or etches it with a slow etching rate.

[0037] Furthermore, if the support layer includes only the transition layer 2, the transition layer 2 needs to provide a certain level of support to the conductive layer 1, and therefore the thickness of the transition layer 2 needs to be increased. If the support layer further includes other structures that can perform a supporting function, the thickness of the transition layer 2 may be reduced. For example, if a carrier layer 3 is provided on the surface of the transition layer 2 away from the conductive layer 1, the carrier layer 3 can provide support to the conductive layer 1, and therefore the thickness of the transition layer 2 may be reduced. Of course, in this case, the thickness of the transition layer 2 may be increased to provide even more support to the conductive layer 1. Therefore, the specific thickness of the transition layer 2 can be set according to the actual usage requirements, and no further explanation is provided here.

[0038] In one selective embodiment, the transition layer 2 is corrosion-resistant to a second etching solution capable of etching the conductive layer 1. This corrosion resistance means that the transition layer 2 is not corroded, is less corroded, or exhibits a slow etching rate by the second etching solution. Because the transition layer 2 is corrosion-resistant to the second etching solution, when manufacturing a circuit board using the metal foil, during the etching process of the conductive layer 1, the transition layer 2 is not corroded, is less corroded, or exhibits a slow etching rate by the second etching solution. The specific type of second etching solution is not particularly limited, and those skilled in the art can select it according to their actual needs as long as the above functions can be achieved.

[0039] In one selective embodiment, the conductive layer 1 is a copper layer, and the transition layer 2 comprises at least one of the elements nickel, chromium, manganese, iron, and cobalt, for example, at least one of nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal. In embodiments of the present invention, the conductive layer 1 is a copper layer, mainly composed of copper, and the transition layer 2 comprises at least one of the elements nickel, chromium, manganese, iron, and cobalt, for example, nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal, and may be mainly composed of nickel-chromium alloy, nickel-phosphorus alloy, or nickel metal, or it may be mainly composed of two or more materials from nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal, or it may be a mixture of at least one material from nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal with other materials. The transition layer 2 may be a single layer or a multilayer structure. If the transition layer 2 is a multilayer structure, it may be, for example, formed by laminating one layer of nickel metal and one layer of nickel-chromium alloy, or by laminating one layer of nickel metal and one layer of nickel-phosphorus alloy, or by laminating one layer of nickel-phosphorus alloy and one layer of nickel-chromium alloy. In actual production, the conductive layer 1 and the transition layer 2 may be unexpectedly contaminated with other impurities, and the unexpected contamination of the conductive layer 1 and the transition layer 2 is also within the scope of protection of the present invention. Furthermore, the conductive layer 1 in the present invention is not limited to a copper layer, nor is the material of the transition layer 2 limited to a nickel-chromium alloy, a nickel-phosphorus alloy, or nickel metal. Conductive layers 1 and transition layers 2 using other materials containing at least one of the elements nickel, chromium, manganese, iron, and cobalt are also within the scope of protection of the present invention. The specific materials and layer structure of the conductive layer 1 and transition layer 2 can be set according to the requirements of actual use. It is sufficient to ensure that the conductive layer 1 has corrosion resistance to the first etching solution and the transition layer 2 has corrosion resistance to the second etching solution. Further explanation is omitted here.For example, if the conductive layer is a copper layer and the transition layer is at least one of a nickel-chromium alloy, a nickel-phosphorus alloy, or nickel metal, the first etching solution may contain sulfuric acid, hydrogen peroxide, and thiourea, or nitric acid, nickel chloride, and imidazole (or nitrogen azoles), or cyanide, and the second etching solution may contain ammonium chloride, copper(II) sulfate pentahydrate, and aqueous ammonia.

[0040] In one selective embodiment, in order to provide sufficient support to the conductive layer 1, the thickness of the support layer in this embodiment is 8 to 105 microns, for example, 8 microns, 10 microns, 15 microns, 20 microns, 25 microns, 30 microns, 35 microns, 40 microns, 45 microns, 50 microns, 55 microns, 60 microns, 65 microns, 70 microns, 75 microns, 80 microns, 85 microns, 90 microns, 95 microns, 100 microns, 105 microns, etc. Of course, the specific thickness of the support layer can be set according to the actual usage requirements, and no further explanation is given here.

[0041] Accordingly, embodiments of the present invention further provide circuit boards manufactured from a substrate and a metal foil according to any of the above embodiments.

[0042] Referring to Figure 8, an embodiment of the present invention is a method for manufacturing a circuit board using the metal foil, Step S101 involves manufacturing a circuit on the conductive layer to obtain a conductive circuit, Step S102 involves connecting the conductive circuit and the substrate, The present invention further provides a method for manufacturing a circuit board, which includes step S103 of removing the support layer.

[0043] In one selective embodiment, after step S103, The process further includes step S104, which involves surface treatment of the conductive circuit so that the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step difference range.

[0044] In practical implementation, surface treatment of the conductive circuit provides an antioxidant effect, and the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step range, further ensuring reliable contact between the conductive circuit and other devices, thereby enabling stable signal transmission.

[0045] In one selective embodiment, step S104, which involves "surface treatment of the conductive circuit such that the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step difference range," specifically, This includes electroplating such that the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step range. For example, referring to Figure 5, one layer of gold is electroplated onto the surface of the conductive circuit 11 such that the surface of the conductive circuit 11 protrudes from the surface of the substrate 5 and the step difference h between it and the surface of the substrate 5 is within a predetermined step range. Of course, other conductive materials may be electroplated onto the conductive circuit depending on the requirements of actual use, and no further explanation is given here. Furthermore, the specific form of the surface treatment is not particularly limited and can be selected by those skilled in the art according to their actual needs, for example, one of electroplating, chemical plating, vapor deposition, sputtering, or a combination thereof may be selected.

[0046] In practical implementation, when surface-treated conductive circuits to prevent oxidation, it is common to choose to electroplat with expensive materials such as gold. However, conventional techniques require thick electroplating of the metal during surface treatment, significantly increasing production costs. This invention significantly reduces production costs compared to conventional techniques because it does not require thick electroplating of the metal. Furthermore, since the surface of the conductive circuit is flat after the support layer is removed, the surface-treated conductive circuit also has a flat surface, allowing the formed circuit board to meet the requirements for high dimensional accuracy.

[0047] Referring to Figure 9, in one selective embodiment, step S101, "to fabricate a circuit on the conductive layer to obtain a conductive circuit," specifically, Step S111 involves applying a film to the conductive layer, where the areas not masked by the mask pattern are non-conductive circuit regions, followed by exposure and development operations to obtain the mask pattern. Step S112 involves etching the non-conductive circuit region using a second etching solution, The process includes step S113, which involves removing the mask pattern to obtain a conductive circuit.

[0048] Referring to Figure 10, in another selective embodiment, step S101, "to manufacture a circuit on the conductive layer to obtain a conductive circuit," specifically, Step S121 involves applying a film to the conductive layer, where the areas not masked by the mask pattern are conductive circuit regions, followed by exposure and development operations to obtain a mask pattern. Step S122 involves thickening the conductive circuit region, for example by electroplating, Step S123 to remove the mask pattern, The process includes step S124, in which high-speed etching is performed using a second etching solution to remove the areas of the conductive layer that are not thickened, thereby obtaining a conductive circuit.

[0049] Furthermore, depending on actual needs, the conductive layer may be thinned before step S121, which involves "applying a film to the conductive layer, exposing it, and developing it to obtain a mask pattern."

[0050] Furthermore, those skilled in the art can manufacture multilayer circuit boards using the aforementioned circuit boards as needed. The number of layers in a multilayer circuit board and the use of embedded circuit boards and / or circuit boards in which conductive circuits protrude from the surface of the board are not particularly limited in this application and can be selected as needed by those skilled in the art.

[0051] Example 2 Referring to Figure 6, the difference between the metal foil of this embodiment and that of Embodiment 1 is that the supporting layer in this embodiment further includes a carrier layer 3, and the transition layer 2 is provided between the carrier layer 3 and the conductive layer 1.

[0052] In the embodiments of the present invention, the carrier layer 3 can be made thinner because it provides greater support capacity. In specific implementations, the transition layer 2 can be formed on the carrier layer 3 by methods such as electroplating, sputtering, vapor deposition, chemical plating, or a combination thereof. It should be noted that if the transition layer 2 has a large thickness to provide sufficient support capacity, it is possible to choose whether or not to provide the carrier layer 3 as needed. The material of the carrier layer 3 is at least one selected from metals and nonmetals, for example, at least one selected from metals, alloys, organic materials, and inorganic materials, and may also be the above-mentioned substances including doping agents. Of course, the thickness and material of the carrier layer 3 can be set according to the requirements of actual use, and no further explanation is given here.

[0053] In one selective embodiment, when a circuit board is manufactured using the metal foil, the carrier layer 3 is removed by peeling. Exemplarily, after peeling off the carrier layer 3, the transition layer 2 may be removed with a first etching solution. Removal of the carrier layer 3 by peeling means that the carrier layer 3 is torn by an external force (e.g., by manual tearing or tearing with a tool).

[0054] In another selective embodiment, when a circuit board is manufactured using the metal foil, the carrier layer 3 is removed by a non-peeling method. Removal of the carrier layer 3 by a non-peeling method means that the carrier layer 3 is removed by a method other than tearing by external force, such as at least one of physical polishing, etching with an etching solution, plasma etching, or laser etching. Exemplarily, the carrier layer 3 is removed by etching with an etching solution, specifically, the material of the transition layer 2 is corrosion-resistant to the third etching solution, and when a circuit board is manufactured using the metal foil, the carrier layer 3 is etched with the third etching solution. Corrosion resistance of the transition layer 2 to the third etching solution means that the transition layer 2 is not corroded, is less corroded, or has a slow etching rate by the third etching solution. Since the transition layer 2 is corrosion-resistant to the third etching solution, when manufacturing a circuit board using the metal foil, the transition layer 2 is not corroded, is less corroded, or has a slow etching rate by the third etching solution during the etching process of the carrier layer 3. Furthermore, the third etching solution may be an etching solution that can etch the conductive layer, or an etching solution that cannot etch the conductive layer, and a person skilled in the art can select it according to their actual needs. Similarly, the third etching solution and the second etching solution may be the same or different. The specific type of the third etching solution is not particularly limited and can be selected by those skilled in the art according to their actual needs. For example, if the conductive layer is a copper layer, the transition layer is at least one of nickel-chromium alloy, nickel-phosphorus alloy, or nickel metal, and the carrier layer is copper, the first etching solution may contain sulfuric acid, hydrogen peroxide, and thiourea, or nitric acid, nickel chloride, and imidazole (or nitrogen azoles), or cyanide. The second and third etching solutions may each independently contain ammonium chloride, copper(II) sulfate pentahydrate, and aqueous ammonia.

[0055] Furthermore, referring to Figure 7, in order to facilitate the peeling of the carrier layer 3, the supporting layer further includes a release layer 4 provided between the carrier layer 3 and the transition layer 2. By providing the release layer 4, the carrier layer 3 can be easily removed by peeling. When peeling the carrier layer 3, the release layer 4 may be peeled off together with the carrier layer 3, a portion of which may remain on the transition layer 2 and need to be peeled off separately, and a portion of which may be peeled off together with the carrier layer 3. In specific implementations, during the manufacturing process of the circuit board, each layer does not fall off unexpectedly.

[0056] Furthermore, for metal foils in which the carrier layer can be peeled off and / or metal foils including a release layer, the sum of the thicknesses of the conductive layer 1 and the transition layer 2 may be 0.2 microns or more in order to facilitate the peeling of the carrier layer and / or release layer during the manufacturing process of the circuit board and not affect the subsequent manufacturing of the circuit board.

[0057] In specific implementations, the conductive layer 1 is a copper layer, and the transition layer 2 contains at least one of the elements nickel, chromium, manganese, iron, and cobalt. In embodiments of the present invention, the conductive layer 1 is a copper layer, mainly composed of copper, and the transition layer 2 contains at least one of the elements nickel, chromium, manganese, iron, and cobalt. Nickel-chromium alloy, nickel-phosphorus alloy, or nickel metal are used as examples. For example, it may be mainly composed of nickel-chromium alloy, nickel-phosphorus alloy, or nickel metal, or it may be mainly composed of two or more materials from nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal, or it may be a mixture of at least one material from nickel-chromium alloy, nickel-phosphorus alloy, and nickel metal with other materials. The transition layer 2 is a single layer or a multilayer structure. If the transition layer 2 is a multilayer structure, for example, it may be formed by laminating one layer of nickel metal and one layer of nickel-chromium alloy, or by laminating one layer of nickel metal and one layer of nickel-phosphorus alloy, or by laminating one layer of nickel-phosphorus alloy and one layer of nickel-chromium alloy. Furthermore, the transition layer 2 may be doped with other materials as needed in practice. For example, silicon may be doped into the transition layer 2. By doping the transition layer 2 with silicon, the barrier effect of the transition layer 2 is increased when etching the carrier layer 3 with an etching solution, further preventing the penetration of the etching solution from the transition layer 2 into the conductive layer 1. In actual production, the conductive layer 1 and the transition layer 2 may be unexpectedly contaminated with other impurities, and the unexpected contamination of the conductive layer 1 and the transition layer 2 is also within the scope of protection of the present invention.Furthermore, the conductive layer 1 in the present invention is not limited to a copper layer, and the material of the transition layer 2 is not limited to a nickel-chromium alloy, a nickel-phosphorus alloy, or nickel metal. Conductive layers 1 and transition layers 2 using other materials containing at least one of the elements nickel, chromium, manganese, iron, and cobalt are also within the scope of protection of the present invention. The specific materials and layer structure of the conductive layer 1 and transition layer 2 can be set according to the requirements of actual use. It is sufficient to ensure that the conductive layer 1 has corrosion resistance to the first etching solution and the transition layer 2 has corrosion resistance to the second etching solution. Further explanation is omitted here.

[0058] Accordingly, the embodiments of the present invention further provide a circuit board manufactured from a substrate and a metal foil of any of the embodiments described above. In addition, the metal foil of Embodiment 2 may be used to manufacture a circuit board using any of the circuit board manufacturing methods according to Embodiment 1.

[0059] Furthermore, a person skilled in the art may manufacture a multilayer circuit board using the aforementioned circuit board as needed. The number of layers of the multilayer circuit board and the use of embedded circuit boards and / or circuit boards in which conductive circuits protrude from the surface of the board are not limited in this application and can be selected by a person skilled in the art as needed.

[0060] Compared to the prior art, the beneficial effects of the embodiment of the present invention are as follows. Specifically, the embodiment of the present invention provides a metal foil comprising a conductive layer 1 and a support layer, wherein the conductive layer 1 and the support layer are laminated together, the conductive layer 1 is used to manufacture a conductive circuit, and when a circuit board is manufactured using the metal foil, the support layer and the conductive layer 1 are separated by a first etching solution, the conductive layer 1 has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer near the conductive layer is 2 microns or less. In the embodiment of the present invention, the surface roughness of the support layer near the conductive layer in the metal foil is 2 microns or less. As a result, the surface of the conductive layer near the support layer also has low roughness. When a conductive circuit is formed with the metal foil according to the embodiment of the present invention and a circuit board is manufactured using the metal foil, the support layer and the conductive layer 1 are separated with the first etching solution. Since the conductive layer has corrosion resistance to the first etching solution, after separating the support layer and the conductive layer with the first etching solution, the surface of the finally formed conductive circuit basically maintains the low surface roughness of the original conductive layer, making it possible to obtain a conductive circuit with a flat surface. Furthermore, after removing the support layer, it is ensured that the surface of the conductive circuit and the surface of the substrate are basically flush. This makes it easier to suppress the step difference between the surface of the conductive circuit and the surface of the substrate, and furthermore, it is possible to meet the demand for products with high dimensional accuracy requirements. Accordingly, the embodiment of the present invention further provides a circuit board and a method for manufacturing a circuit board.

[0061] The above are merely preferred embodiments of the present invention, and it should be noted that those skilled in the art can make several improvements and substitutions without departing from the technical principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. [Explanation of symbols]

[0062] 10. Conductive circuit; 20. Substrate; 1. Conductive layer; 2. Transition layer; 3. Carrier layer; 4. Delamination layer; 11. Conductive circuit; 5. Substrate.

Claims

1. A metal foil comprising a conductive layer and a support layer, The conductive layer and the support layer are laminated together, the conductive layer is used to manufacture a conductive circuit, and when manufacturing a circuit board with the metal foil, the support layer and the conductive layer are separated by a first etching solution, the conductive layer has corrosion resistance to the first etching solution, and the surface roughness Rz of the support layer near the conductive layer is 2 microns or less. The support layer includes a transition layer as the separation configuration, the transition layer and the conductive layer are arranged in a laminated manner, and the transition layer is etched with the first etching solution so that the support layer and the conductive layer are separated. The metal foil is characterized in that the transition layer has corrosion resistance to a second etching solution that can etch the conductive layer.

2. The metal foil according to claim 1, characterized in that the surface roughness Rz of the support layer near the conductive layer is 1 micron or less.

3. The metal foil according to claim 1, characterized in that the conductive layer is a copper layer, and the transition layer contains at least one of the elements nickel, chromium, manganese, iron, and cobalt.

4. The metal foil according to claim 1, characterized in that the thickness of the support layer is 8 to 105 microns.

5. The metal foil according to claim 1, characterized in that the supporting layer further includes a carrier layer, and the transition layer is provided between the carrier layer and the conductive layer.

6. The metal foil according to claim 5, characterized in that the material of the carrier layer is at least one selected from metals and nonmetals.

7. The metal foil according to claim 5, characterized in that when a circuit board is manufactured using the metal foil, the carrier layer is removed by a non-peeling method.

8. The metal foil according to claim 5, characterized in that when a circuit board is manufactured using the metal foil, the carrier layer is removed by peeling.

9. The material of the transition layer is corrosion-resistant to the third etching solution, and when a circuit board is manufactured using the metal foil, the carrier layer is etched with the third etching solution, as described in claim 5.

10. The metal foil according to claim 5, characterized in that the supporting layer further includes a release layer provided between the carrier layer and the transition layer.

11. The metal foil according to claim 8, characterized in that the sum of the thicknesses of the conductive layer and the transition layer is 0.2 microns or more.

12. A circuit board characterized by being manufactured from a substrate and a metal foil according to any one of claims 1 to 11.

13. A method for manufacturing a circuit board using a metal foil as described in any one of claims 1 to 11, The steps include: manufacturing a circuit on the conductive layer to obtain a conductive circuit, The steps include connecting the conductive circuit and the substrate, A method for manufacturing a circuit board, comprising the step of removing the support layer.

14. After the step of removing the support layer, The method for manufacturing a circuit board according to claim 13, further comprising the step of performing a surface treatment on the conductive circuit so that the step difference between the surface of the conductive circuit and the surface of the substrate is within a predetermined step difference range.

15. The step of manufacturing a circuit on the conductive layer to obtain a conductive circuit is, specifically, The steps include: applying a film to the conductive layer, where the areas not masked by the mask pattern are non-conductive circuit regions, and then performing exposure and development operations to obtain the mask pattern; The steps include etching the non-conductive circuit region using a second etching solution, A method for manufacturing a circuit board according to claim 13, comprising the step of removing the mask pattern to obtain a conductive circuit.

16. The step of manufacturing a circuit on the conductive layer to obtain a conductive circuit is, specifically, The steps include: applying a film to the conductive layer, where the areas not masked by the mask pattern are conductive circuit regions, and then performing exposure and development operations to obtain the mask pattern; The steps of increasing the thickness of the conductive circuit region, The step of removing the mask pattern, A method for manufacturing a circuit board according to claim 13, comprising the step of performing high-speed etching using a second etching solution to remove areas of the conductive layer that are not thickened, thereby obtaining a conductive circuit.

17. Before the step of applying a film to the conductive layer, exposing it, and developing it to obtain a mask pattern, The method for manufacturing a circuit board according to claim 16, further comprising the step of thinning the conductive layer.

18. A multilayer circuit board characterized by including the circuit board described in claim 12.

19. A method for manufacturing a multilayer circuit board, characterized by including the method for manufacturing a circuit board described in claim 13.

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