Peelable metal foil and metal-clad laminated plate

Abstract

According to the peelable metal foil and the metal-clad laminated plate disclosed by the invention, after a carrier layer is peeled from a functional layer through a peeling layer, a brownification layer is formed by performing brownification processing on the residual peeling layer on one side of the functional layer, so that the laser absorptivity of the functional layer on one side with the brownification layer can be effectively improved, and the drilling efficiency can be improved; in addition, the change rate between the actual area and the preset area of any hole formed by performing laser drilling on the optimized brownification layer is smaller than or equal to 10%, and it is indicated that the drilling hole pattern yield can be effectively guaranteed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electronic information materials, and in particular to a peelable metal foil and a metal-clad laminated board. BACKGROUND

[0002] The peelable metal foil with a carrier is widely used in laminating with a base material through hot pressing, and then the carrier layer in the peelable metal foil is peeled off, and the functional layer, such as a thin copper layer, is used as a metal-clad laminated board. When a super-fine line is manufactured by using an MSAP (Modified Semi-Additive Process) process, a laser is used to drill holes in the board after the functional layer is laminated on the base material. The finer the line, the smaller the hole size designed to match. The existing peelable metal foil has a high gloss on the surface of the functional layer after lamination, and the laser is difficult to be absorbed by the functional layer during laser drilling, thereby resulting in low drilling efficiency and prone to drilling hole defects. SUMMARY

[0003] The present application provides a peelable metal foil and a metal-clad laminated board. After the carrier layer is peeled off from the functional layer through the peeling layer, a brown layer is formed by brown processing on the residual peeling layer on one side of the functional layer, which can effectively improve the laser absorption rate of the functional layer on the side with the brown layer, thereby improving the drilling efficiency and the drilling hole yield.

[0004] To solve the above technical problems, the first aspect of the embodiment of the present application provides a peelable metal foil, comprising a carrier layer, a peeling layer and a functional layer, the peeling layer is arranged between the carrier layer and the functional layer;

[0005] After the carrier layer is peeled off from the functional layer through the peeling layer, part of the peeling layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned. The change rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and its preset area S0 is less than or equal to 10%; wherein ΔS = |S-S0| / S0.

[0006] As a preferred scheme, the range variation rate between the actual areas of any two holes formed on the brown layer by laser drilling is less than or equal to 5%;

[0007] Wherein, the range variation rate is obtained by the following expression:

[0008] ΔK = 2|S1-S2| / (S1+S2);

[0009] ΔK represents the range variation rate, S1 and S2 are the actual areas of the two holes.

[0010] As a preferred solution, in the state of slicing, the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer is less than or equal to 2 μm within any 100 μm length.

[0011] As a preferred solution, the ratio of the actual surface area of the brown layer to its projected area is 2-10.

[0012] As a preferred solution, the content of the iron element in the brown layer is 50 mg / m 2 ~ 200 mg / m 2 , and the content of the nickel element is less than or equal to 40 mg / m 2 .

[0013] As a preferred solution, the peeling force of the peeling layer close to the functional layer side is less than the peeling force of the peeling layer close to the carrier layer side.

[0014] As a preferred solution, the peeling strength between the carrier layer and the functional layer is 0.2 N / cm-1 N / cm.

[0015] As a preferred solution, the material of the peeling layer is an organic material, an inorganic material or a mixed material; wherein the mixed material includes the organic material and the inorganic material.

[0016] As a preferred solution, a heat-resistant layer is further included, which is arranged on the side surface of the carrier layer away from the peeling layer.

[0017] The second aspect of the embodiment of the present application provides a metal-clad laminate, which is made of the functional layer in the peelable metal foil as any one of the first aspect as one of the materials.

[0018] Compared with the prior art, the beneficial effects of the embodiment of the present application are that after the carrier layer is peeled from the functional layer through the peeling layer, the brown layer is formed by brown processing on the residual peeling layer on the side of the functional layer, which can effectively improve the laser absorption rate of the functional layer on the side with the brown layer, thereby improving the drilling efficiency; in addition, the change rate between the actual area of any one hole formed by laser drilling on the optimized brown layer and its preset area is less than or equal to 10%, which indicates that the present application can effectively ensure the drilling hole type yield. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structure schematic diagram of the first peelable metal foil in the embodiment of the present application;

[0020] Figure 2 is a structure schematic diagram of the peelable metal foil after the carrier layer is peeled and laminated on the circuit board substrate in the embodiment of the present application;

[0021] Figure 3 is a structure diagram of the residual layer after brownification of the peelable metal foil in the embodiment of the present application being pressed on the circuit board substrate;

[0022] Figure 4 is a structure diagram of the second peelable metal foil in the embodiment of the present application;

[0023] In the figure, 1 is a carrier layer; 2 is a peelable layer; 3 is a functional layer; 4 is a residual layer; 5 is a brownification layer; 6 is a heat-resistant layer; and 7 is a circuit board substrate. DETAILED DESCRIPTION

[0024] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments of the present application. The purpose of providing these embodiments is to make the disclosure of the present application more thorough and comprehensive. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative efforts fall within the scope of protection of the present application.

[0025] In the description of the present application, the terms “first”, “second”, “third”, etc. are used only for the purpose of description, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with “first”, “second”, “third”, etc. can explicitly or implicitly include one or more of the features. In the description of the present application, unless otherwise specified, the meaning of “a plurality of” is two or more.

[0026] In the description of the present application, it should be noted that, unless otherwise explicitly specified and limited, the terms “mounting”, “connection”, “connection” should be understood in a broad sense, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. The terms “vertical”, “horizontal”, “left”, “right”, “up”, “down” and similar expressions used in this paper are only for the purpose of description, and cannot be understood as indicating or implying that the devices or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present application. The term “and / or” used in this paper includes any and all combinations of one or more related listed items. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0027] In the description of the present application, it is necessary to explain that, unless otherwise defined, all the technical and scientific terms used in the present application are the same as the meanings commonly understood by the person skilled in the art belonging to the technical field of the present application. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application, and the specific meanings of the above terms in the present application can be understood by the person skilled in the art according to the specific circumstances.

[0028] Please refer to Figures 1 to 3 The first aspect of the embodiment of the present application provides a peelable metal foil, comprising a carrier layer 1, a peel layer 2 and a functional layer 3, the peel layer 2 is arranged between the carrier layer 1 and the functional layer 3.

[0029] After the carrier layer 1 is peeled from the functional layer 3 through the peel layer 2, part of the peel layer 2 remains on one side of the functional layer 3 to form a residual layer 4, and the residual layer 4 forms a brown layer 5 on one side of the functional layer 3 after brownization; the change rate ΔS between the actual area S of any one hole formed on the brown layer 5 by laser drilling and its preset area S0 is less than or equal to 10%; wherein ΔS = |S-S0| / S0.

[0030] It is worth noting that the carrier layer 1 is arranged on other material layers such as the functional layer 3 in the metal foil in actual application, used to carry and protect the functional layer 3, so that the functional layer 3 is not damaged by external contact or collision, or to meet the more precise line manufacturing process requirements, after the functional layer 3 is high-temperature compression bonded on the circuit board substrate 7, the carrier layer 1 needs to be peeled off. In the present embodiment, the material of the carrier layer 1 can include any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, which is not specifically limited in the present embodiment.

[0031] The functional layer 3 plays a role of conducting electricity, and the material of the functional layer 3 can include any one of aluminum, titanium, zinc, iron, nickel, chromium, cobalt, copper, silver and gold, which is not excessively described in the present embodiment. In actual application, for example, in the field of circuit board, the functional layer 3 is thermally compressed and bonded with the circuit board substrate 7, for example, in the field of electronic material production, the functional layer 3 made of copper material is combined with other composite materials to make copper-clad plate, flexible copper-clad plate, or as a production raw material of copper-clad adhesive foil, for example, in the field of battery, the functional layer 3 made of copper material is used as the negative electrode material (negative electrode current collector) of the battery, which is thermally compressed and bonded with the negative electrode active material in the negative electrode material, and the functional layer 3 made of aluminum material is used as the positive electrode material (positive electrode current collector) of the battery.

[0032] The role of the peeling layer 2 is to achieve the separation of the carrier layer 1 and the functional layer 3 by peeling; meanwhile, the peeling layer 2 can block the metal migration between the functional layer 3 and the carrier layer 1, and can cover or fill the uneven surface of the carrier layer 1, so that the functional layer 3 formed on the other surface of the peeling layer 2 is more flat, uniform and dense, and the occurrence of pinholes is reduced, thereby being beneficial to the subsequent circuit manufacturing. In the specific implementation process, when the carrier layer 1 is removed by peeling, the peeling can be directly removed by manual peeling or by mechanical equipment.

[0033] In the embodiment, in order to avoid that the peelable metal foil is difficult to absorb laser when laser drilling after being pressed on the circuit board substrate 7, the carrier layer 1 is peeled from the functional layer 3, and part of the peeling layer 2 still remains on one side of the functional layer 3 to form a residual layer 4, as shown in Figure 2 The residual layer 4 is browned by brown solution, so that a brown layer 5 is formed on one side of the functional layer 3, as shown in Figure 3 Since the color of the brown layer 5 is deep and the absorption energy of laser is high, when laser drilling is performed on the side of the functional layer 3 with the brown layer 5, the laser absorption rate can be significantly improved compared with directly laser drilling on the surface of the functional layer 3 with high gloss, so that the drilling efficiency can be improved.

[0034] Further, the change rate ΔS between the actual area S of any one hole formed by laser drilling and the preset area S0 of the hole is less than or equal to 10% after laser drilling on the brown layer 5, for example, the change rate ΔS can be 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0, etc., which is not limited in the embodiment. It can be understood that the change rate in the embodiment is the ratio between the difference between the actual area of the hole and the preset area of the hole and the preset area. The actual area of the hole refers to the real area measured after laser drilling, and the preset area refers to the target area obtained according to the process requirement before laser drilling. The preset area can be set according to the actual process requirement, which is not limited in the embodiment. The change rate of each hole formed by laser drilling on the brown layer 5 in the embodiment is within 10%, which indicates that the deviation between the actual area and the preset area of each hole is not large, and the drilling hole type yield is effectively ensured, and problems such as uneven hole type, large burr in the hole wall or irregular hole type are avoided.

[0035] As a preferred scheme, the range change rate between the actual areas of any two holes formed on the brown layer 5 by laser drilling is less than or equal to 5%;

[0036] The range variation rate is calculated by the following expression:

[0037] △K = 2|S1-S2| / (S1+S2);

[0038] △K represents the range variation rate, and S1 and S2 are the actual areas of the two arbitrary holes, respectively.

[0039] Specifically, the range variation rate between the actual areas of the two arbitrary holes formed on the brown layer 5 by laser drilling is less than or equal to 5%, for example, the range variation rate can be 5%, 4.5%, 4%, 3.5%, 3%, 2.5%, 2%, 1.5%, 1%, 0.5%, 0, etc., which can ensure that the actual areas of the holes formed by laser drilling are uniform and consistent in size, thereby ensuring the stability of laser drilling and improving the drilling hole type yield.

[0040] It is worth noting that in the expression: △K = 2|S1-S2| / (S1+S2), assuming that the two arbitrary holes formed on the brown layer 5 by laser drilling are respectively referred to as a first hole and a second hole, then S1 and S2 are the actual areas of the first hole and the second hole, respectively, for example, S1 represents the actual area of the first hole, and S2 represents the actual area of the second hole; or, S1 represents the actual area of the second hole, and S2 represents the actual area of the first hole, which is not specifically limited in the present embodiment.

[0041] As a preferred solution, in the sliced state, the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer 5 is less than or equal to 2 μm within any 100 μm length.

[0042] Specifically, the functional layer 3 with the brown layer 5 is sliced, and the sliced state is observed under an electron microscope. In an arbitrary 100 μm length region, the peak-valley profile of the brown layer 5 is observed, and the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer 5 is limited to be less than or equal to 2 μm, for example, the height difference is 2 μm, 1.8 μm, 1.5 μm, 1.3 μm, 1.1 μm, 1 μm, 0.8 μm, 0.6 μm, 0.5 μm, 0.3 μm, 0.1 μm, etc., which is not specifically limited in the present embodiment, thereby ensuring that the undulation of the brown layer 5 is low, and the surface of the brown layer 5 is overall flat and uniform, and further improving the laser absorption rate of the functional layer 3 on the side with the brown layer 5.

[0043] As a preferred solution, the ratio of the actual surface area of the brown layer 5 to its projection area is 2-10.

[0044] Specifically, the projected area of the brown layer 5 in the embodiment is the area of the projection region in the projection direction perpendicular to the brown layer 5, and the actual surface area of the brown layer 5 is the total area occupied by the surface (including protrusions, recesses, pores, etc.) of the brown layer 5. By limiting the ratio of the actual surface area of the brown layer 5 to the projected area thereof to 2-10, for example, the ratio can be 2, 3, 4, 5, 6, 7, 8, 9, 10, etc., which is not specifically limited in the embodiment, so as to improve the laser absorption rate of the functional layer 3 on the side with the brown layer 5. At the same time, the embodiment avoids that the ratio of the actual surface area of the brown layer 5 to the projected area thereof is too large, which easily leads to the phenomenon that the etching is not uniform during subsequent micro-etching, thereby affecting the stability of the subsequent circuit.

[0045] As a preferred solution, the content of the iron element in the brown layer 5 is 50 mg / m 2 ~200 mg / m 2 , and the content of the nickel element is less than or equal to 40 mg / m 2 .

[0046] Specifically, the embodiment further limits the content of the iron element in the brown layer 5 to 50 mg / m 2 ~200 mg / m 2 , and the content of the nickel element is less than or equal to 40 mg / m 2 , for example, in the brown layer 5, the content of the iron element can be 50 mg / m 2 , 75 mg / m 2 , 100 mg / m 2 , 112 mg / m 2 , 125 mg / m 2 , 136 mg / m 2 , 148 mg / m 2 , 159 mg / m 2 , 160 mg / m 2 , 172 mg / m 2 , 180 mg / m 2 , 190 mg / m 2 , 200 mg / m 2 , and the content of the nickel element can be 5 mg / m 2 , 8 mg / m 2 , 14 mg / m 2 , 18 mg / m 2 , 20 mg / m 2 , 25 mg / m 2 , 30 mg / m 2 , 34 mg / m 2 , 38 mg / m 2 , 40 mg / m 2In addition, the content of iron element is relatively high, which can effectively improve the color depth of the brown layer 5, improve the absorption rate of laser, improve the drilling hole type yield, limit the content of nickel element, avoid the brown stripes and high gloss caused by too much nickel element, and affect the appearance and laser absorption rate. In addition, too much iron element and too little nickel element can avoid the subsequent micro-etching effect, because iron element is easy to be removed by micro-etching, while nickel element is difficult to be removed by micro-etching. Therefore, by adding more iron element in the brown layer 5 and limiting the content of nickel element, the laser drilling efficiency can be effectively improved without affecting the subsequent micro-etching process.

[0047] As a preferred solution, the peeling force of the peeling layer 2 close to the functional layer 3 is less than the peeling force of the peeling layer 2 close to the carrier layer 1.

[0048] Specifically, by limiting the peeling force of the peeling layer 2 close to the functional layer 3 to be less than the peeling force of the peeling layer 2 close to the carrier layer 1, when the carrier layer 1 is peeled off after the peelable metal foil is pressed and combined on the circuit board substrate 7, the peeling can be performed from the peeling interface between the peeling layer 2 and the functional layer 3, so that the carrier layer 1 can be completely peeled off from the functional layer 3 through the peeling layer 2, avoiding the residue of the carrier layer 1 on the functional layer 3, and ensuring the peeling stability of the peelable metal foil.

[0049] As a preferred solution, the peeling strength between the carrier layer 1 and the functional layer 3 is 0.2N / cm-1N / cm.

[0050] Specifically, if the peeling strength between the functional layer 3 and the carrier layer 1 is too large, the carrier layer 1 is difficult to be peeled off from the functional layer 3, and the functional layer 3 is easy to be damaged. If the peeling strength is too small, the functional layer 3 is easy to automatically fall off from the carrier layer 1. Therefore, by limiting the peeling strength between the functional layer 3 and the carrier layer 1 to be 0.2N / cm-1N / cm, for example, the peeling strength between the functional layer 3 and the carrier layer 1 can be 0.2N / cm, 0.3N / cm, 0.4N / cm, 0.5N / cm, 0.6N / cm, 0.7N / cm, 0.8N / cm, 0.9N / cm, 1N / cm, etc. The embodiment is not limited here, so that the carrier layer 1 is not difficult to be peeled off from the functional layer 3 due to too large peeling force, and the functional layer 3 is not easy to automatically fall off from the carrier layer 1 due to too small peeling force, which can effectively ensure the peeling stability of the peelable metal foil, and is beneficial to improve the use reliability and processing efficiency of the peelable metal foil.

[0051] As a preferred solution, the material of the peeling layer 2 is an organic material, an inorganic material or a mixed material; wherein the mixed material includes the organic material and the inorganic material.

[0052] Specifically, the material of the peeling layer 2 in the embodiment can be an organic material, such as a nitrogen-containing compound, a sulfur-containing compound, a carboxylic acid, and the like. The nitrogen-containing organic compound includes the following types: a ketoxime compound, a transition metal chelating agent, an organic amine compound, and a nitrogen heterocyclic compound; the ketoxime compound includes a phenyl oxime, an o-nitrophenyl oxime, and the like; the transition metal chelating agent includes a nitrosopropionone, and the like; the organic amine compound includes aniline, diethylamine, and the like; the nitrogen heterocyclic compound includes pyridine, imidazole, and the like; of course, in addition to the above-mentioned nitrogen-containing organic compounds, other nitrogen-containing organic compounds can also be used, and the embodiment will not be described in detail here. The types of the sulfur-containing organic compound include a disulfide compound and a thioether compound; the disulfide compound includes ethylene disulfide, propylene disulfide, and the like; the thioether compound includes thioanisole, thioethyl ether, and the like; of course, in addition to the above-mentioned sulfur-containing organic compounds, other sulfur-containing organic compounds can also be used, and the embodiment will not be described in detail here.

[0053] In addition, the material of the peeling layer 2 in the embodiment can also be an inorganic material, including a metal-based layer or an alloy layer, such as an alloy made of any one or more of copper, nickel, silicon, molybdenum, titanium, and niobium, and the embodiment will not be specifically limited here.

[0054] In addition, the material of the peeling layer 2 in the embodiment can also be a mixed material including an organic material and an inorganic material. The organic material can include the above-mentioned nitrogen-containing compound, sulfur-containing compound, and carboxylic acid, and the like, and the inorganic material can include the above-mentioned alloy made of any one or more of copper, nickel, silicon, molybdenum, titanium, and niobium, and the embodiment will not be specifically limited here.

[0055] In the embodiment, the peeling layer 2 is processed on the carrier layer 1 by any one of an electroplating process, a vacuum sputtering process, and a coating process.

[0056] As a preferred solution, a heat-resistant layer 6 is further included, which is arranged on the side surface of the carrier layer 1 away from the peeling layer 2.

[0057] Specifically, please refer to Figure 4In order to enhance the high-temperature resistance of the peelable metal foil during hot pressing, the heat-resistant layer 6 is arranged on the side surface of the carrier layer 1 away from the peeling layer 2, and it can be understood that, during the high-temperature pressing of the functional layer 3 and the circuit board substrate, the carrier layer 1 may be in contact with the high-temperature pressing plate of the pressing machine and thus be melted or deformed, thereby affecting the structural stability of the peelable metal foil, and even causing the carrier layer 1 and the functional layer 3 to diffuse with each other at high temperature and thus be difficult to peel. The heat-resistant layer 6 can play a heat insulation role, reduce the heating temperature of the carrier layer 1 and the peeling layer 2, and ensure the thermal stability of the carrier layer 1 and the peeling layer 2. The material of the heat-resistant layer 6 can be: tetrafluoroethylene film, polyimide film, heat-resistant adhesive, etc., and the above materials all have certain heat resistance and can effectively protect the peelable metal foil from being damaged by heat during pressing.

[0058] The second aspect of the embodiment of the present application provides a metal-clad laminate made of the functional layer in the peelable metal foil as described in any one of the first aspect.

[0059] The peelable metal foil and the metal-clad laminate provided by the embodiment of the present application have at least the following beneficial effects:

[0060] (1) After the carrier layer is peeled from the functional layer through the peeling layer, a brown layer is formed by brown processing on the residual peeling layer on one side of the functional layer, which can effectively improve the laser absorption rate of the functional layer on the side with the brown layer, thereby improving the drilling efficiency; in addition, the change rate between the actual area of any one hole formed by laser drilling on the optimized brown layer and the preset area thereof is less than or equal to 10%, which can effectively ensure the drilling hole type yield.

[0061] (2) By limiting the range variation rate between the actual areas of any two holes formed by laser drilling on the brown layer to be less than or equal to 5%, it can be ensured that the actual areas of each hole formed by laser drilling are uniform and consistent in size, thereby ensuring the stability of laser drilling and improving the drilling hole type yield.

[0062] (3) By limiting the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer in a region of 100 μm in length to be less than or equal to 2 μm, it can be ensured that the entire browned surface is relatively flat and uniform, thereby improving the laser absorption rate of the functional layer on the side with the brown layer.

[0063] (4) By limiting the ratio of the actual surface area of the brown layer to its projected area to 2-10, the laser absorption rate of the functional layer on the side with the brown layer can be improved, while avoiding the phenomenon of uneven etching during subsequent micro-etching caused by the ratio of the actual surface area of the brown layer to its projected area being too large, thereby affecting the stability of the subsequent circuit.

[0064] (5) By adding more iron elements and limiting the content of nickel elements in the brown layer, the laser drilling efficiency can be effectively improved without affecting the subsequent micro-etching process.

[0065] In order to fully embody the beneficial effects of the peelable metal foil and metal-clad laminate provided by the embodiments of the present application, several examples and comparative examples are described below.

[0066] Example 1

[0067] A peelable metal foil includes a carrier layer, a peel layer, and a functional layer, the peel layer is arranged between the carrier layer and the functional layer; after the carrier layer is peeled from the functional layer through the peel layer, part of the peel layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned; the change rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and its preset area S0 is 4.2%-8.3%.

[0068] Example 2

[0069] A peelable metal foil includes a carrier layer, a peel layer, and a functional layer, the peel layer is arranged between the carrier layer and the functional layer; after the carrier layer is peeled from the functional layer through the peel layer, part of the peel layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned; the change rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and its preset area S0 is 6.8%-10%.

[0070] The range change rate between the actual areas of any two holes formed on the brown layer by laser drilling is 3.2%-5%.

[0071] Example 3

[0072] A peelable metal foil includes a heat-resistant layer, a carrier layer, a peel layer, and a functional layer arranged in sequence; after the carrier layer is peeled from the functional layer through the peel layer, part of the peel layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned; the change rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and its preset area S0 is 2.4%-5.6%.

[0073] The range variation rate between the actual areas of any two holes formed on the brown layer by laser drilling is 1.4% to 3%. The functional layer with the brown layer is sliced, and under the electron microscope, the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer is 1.5 μm in a 100 μm length region. The ratio of the actual surface area of the brown layer to the projected area thereof is 4.

[0074] Example 4

[0075] A peelable metal foil includes a heat-resistant layer, a carrier layer, a peel layer, and a functional layer which are sequentially stacked; after the carrier layer is peeled from the functional layer through the peel layer, part of the peel layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned; the variation rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and the preset area S0 thereof is 1.5% to 6%.

[0076] The range variation rate between the actual areas of any two holes formed on the brown layer by laser drilling is 0.5% to 2.6%. The functional layer with the brown layer is sliced, and under the electron microscope, the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer is 2 μm in a 100 μm length region. The ratio of the actual surface area of the brown layer to the projected area thereof is 6.

[0077] The content of iron element in the brown layer is 50 mg / m 2 , and the content of nickel element is 20 mg / m 2 . The peel strength between the carrier layer and the functional layer is 0.6 N / cm.

[0078] Example 5

[0079] A peelable metal foil includes a heat-resistant layer, a carrier layer, a peel layer, and a functional layer which are sequentially stacked; after the carrier layer is peeled from the functional layer through the peel layer, part of the peel layer remains on one side of the functional layer to form a residual layer, and the residual layer forms a brown layer on one side of the functional layer after being browned; the variation rate ΔS between the actual area S of any one hole formed on the brown layer by laser drilling and the preset area S0 thereof is 6.7% to 9%.

[0080] The range variation rate between the actual areas of any two holes formed on the brown layer by laser drilling is 1.8% to 4.5%. The functional layer with the brown layer is sliced, and under the electron microscope, the height difference between the highest point and the lowest point of the peak-valley profile of the brown layer is 0.8 μm in a 100 μm length region. The ratio of the actual surface area of the brown layer to the projected area thereof is 2.5.

[0081] The content of iron element in the brown layer is 150 mg / m 2 and the content of nickel element is 40 mg / m 2 The peeling strength between the carrier layer and the functional layer is 0.8 N / cm.

[0082] Comparative Example 1

[0083] A peelable metal foil includes a carrier layer, a peeling layer and a functional layer, the peeling layer is arranged between the carrier layer and the functional layer; after the carrier layer is peeled from the functional layer through the peeling layer, a brown layer is formed on one side of the functional layer by performing brown processing on the residual peeling layer.

[0084] The peelable metal foils in each of the above examples and comparative examples are respectively laminated on the same circuit board substrate, and an ultra-fine circuit is made by using MSAP process, and the drilling hole type yield of each peelable metal foil is tested, and the test results are shown in Table 1.

[0085] Table 1: Drilling hole type yield of each peelable metal foil

[0086] Inspection object Drilling hole profile yield Example 1 96％ Example 2 95％ Example 3 97％ Example 4 98％ Example 5 96％ Comparative Example 1 73％

[0087] It can be seen that, since the peelable metal foils in Examples 1-5 form a brown layer on one side of the functional layer by performing brown processing on the residual peeling layer after the carrier layer is peeled from the functional layer, and the change rate between the actual area of any one hole formed by laser drilling on the optimized brown layer and its preset area is less than or equal to 10%, the laser absorption rate can be significantly improved during the laser drilling process due to the deep color of the brown layer, thereby improving the drilling efficiency, effectively avoiding the occurrence of problems such as uneven hole type, excessive burr on the inner wall of the hole, and irregular hole type, and ensuring the drilling hole type yield.

[0088] The peelable metal foil in Comparative Example 1 does not form a residual layer and perform processing to form a brown layer on one side of the functional layer after the carrier layer is peeled from the functional layer, so that during the laser drilling process, the laser is difficult to be absorbed by the functional layer due to the high gloss of the surface of the functional layer, thereby leading to low drilling efficiency, and problems such as uneven hole type, excessive burr on the inner wall of the hole, and irregular hole type, resulting in low drilling hole type yield.

[0089] The above is a preferred embodiment of the present application, it should be noted that for ordinary skilled in the art, without departing from the principles of the present application, can make a number of improvements and refinements, these improvements and refinements also considered as the protection scope of the present application.

Claims

1. A peelable metal foil, characterized in that, It includes a carrier layer, a release layer, and a functional layer, wherein the release layer is disposed between the carrier layer and the functional layer; After the carrier layer is peeled off from the functional layer by the peeling layer, a portion of the peeling layer remains on one side of the functional layer to form a residual layer. After browning, the residual layer forms a browned layer on one side of the functional layer. The rate of change between the actual area S of any hole formed by laser drilling on the browned layer and its preset area S0 is less than or equal to 10%. Wherein, ΔS = |S-S0| / S0.

2. The peelable metal foil as described in claim 1, characterized in that, The range of variation between the actual areas of any two holes formed by laser drilling on the browning layer is less than or equal to 5%. The range change rate is calculated using the following expression: △K=2|S1-S2| / (S1+S2); △K represents the range change rate, and S1 and S2 are the actual areas of any two holes, respectively.

3. The peelable metal foil as described in claim 1, characterized in that, In the sliced ​​state, within any length of 100 μm, the height difference between the highest and lowest points of the peak-valley profile of the browning layer is less than or equal to 2 μm.

4. The peelable metal foil as described in claim 1, characterized in that, The ratio of the actual surface area of ​​the browning layer to its projected area is 2 to 10.

5. The peelable metal foil as described in claim 1, characterized in that, The iron content in the browning layer is 50 mg / m³. 2 ~200mg / m 2 And the nickel content is less than or equal to 40 mg / m³. 2 .

6. The peelable metal foil as described in claim 1, characterized in that, The peeling force of the peeling layer on the side closer to the functional layer is less than the peeling force of the peeling layer on the side closer to the carrier layer.

7. The peelable metal foil as described in claim 1, characterized in that, The peel strength between the carrier layer and the functional layer is 0.2 N / cm to 1 N / cm.

8. The peelable metal foil as described in claim 1, characterized in that, The material of the peeling layer is an organic material, an inorganic material, or a mixed material; wherein, the mixed material includes both the organic material and the inorganic material.

9. The peelable metal foil as described in claim 1, characterized in that, It also includes a heat-resistant layer disposed on the surface of the carrier layer away from the release layer.

10. A metal-clad laminate, characterized in that, The metal-clad laminate is made using a functional layer of the peelable metal foil as described in any one of claims 1 to 9 as one of the materials.

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