CN115038238A - Metal foil and printed circuit board - Google Patents

Metal foil and printed circuit board Download PDF

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Publication number
CN115038238A
CN115038238A CN202210958771.6A CN202210958771A CN115038238A CN 115038238 A CN115038238 A CN 115038238A CN 202210958771 A CN202210958771 A CN 202210958771A CN 115038238 A CN115038238 A CN 115038238A
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China
Prior art keywords
metal
metal foil
layer
nodules
maximum diameter
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Granted
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CN202210958771.6A
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Chinese (zh)
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CN115038238B (en
Inventor
李冬梅
周涵钰
姚向荣
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Zhuhai Dachuang Electronics Co ltd
Guangzhou Fangbang Electronics Co Ltd
Original Assignee
Zhuhai Dachuang Electronics Co ltd
Guangzhou Fangbang Electronics Co Ltd
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Priority to CN202210958771.6A priority Critical patent/CN115038238B/en
Publication of CN115038238A publication Critical patent/CN115038238A/en
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/0213—Electrical arrangements not otherwise provided for
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/01—Layered products comprising a layer of metal all layers being exclusively metallic
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/04—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B15/08—Layered products comprising a layer of metal comprising metal as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B15/00—Layered products comprising a layer of metal
    • B32B15/20—Layered products comprising a layer of metal comprising aluminium or copper
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B33/00—Layered products characterised by particular properties or particular surface features, e.g. particular surface coatings; Layered products designed for particular purposes not covered by another single class
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/06—Interconnection of layers permitting easy separation
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/005—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile
    • B32B9/007—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising one layer of ceramic material, e.g. porcelain, ceramic tile comprising carbon, e.g. graphite, composite carbon
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B9/041—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of metal
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B9/00—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00
    • B32B9/04—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material
    • B32B9/045—Layered products comprising a layer of a particular substance not covered by groups B32B11/00 - B32B29/00 comprising such particular substance as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/09—Use of materials for the conductive, e.g. metallic pattern
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K1/00—Printed circuits
    • H05K1/02—Details
    • H05K1/11—Printed elements for providing electric connections to or between printed circuits
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/20—Properties of the layers or laminate having particular electrical or magnetic properties, e.g. piezoelectric
    • B32B2307/202—Conductive
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/714—Inert, i.e. inert to chemical degradation, corrosion
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B2457/00—Electrical equipment
    • B32B2457/08—PCBs, i.e. printed circuit boards
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Ceramic Engineering (AREA)
  • Chemical & Material Sciences (AREA)
  • Parts Printed On Printed Circuit Boards (AREA)

Abstract

The invention discloses a metal foil and a printed circuit board. The metal foil comprises a roughened surface, a plurality of metal grains and a plurality of metal nodules are arranged on the roughened surface, the magnification of a scanning electron microscope is 20000 times, and the observation area is 420 mu m 2 In the observation field of (2), the number X of the metal nodules satisfies X is less than or equal to 12, and the maximum diameter W of the metal nodules satisfies 0.1 mu m is less than or equal to W is less than or equal to 6 mu m. By adopting the technical means of the invention, the structure of the metal tumor on the coarsened surface of the metal foil is optimized, so that the crystal grains on the coarsened surface are uniformly distributed, the structure of the metal foil is optimized, the quality of the metal foil is effectively improved, the stress concentration of the metal foil is reduced, the risk of damage in the transportation and all the time process is reduced, and the reject ratio of products applying the metal foil is also reduced.

Description

Metal foil and printed circuit board
Technical Field
The invention relates to the technical field of metal foils, in particular to a metal foil and a printed circuit board.
Background
In recent years, with the increasing demand for miniaturization and high performance of electronic devices, high-density mounting of mounted components has been advanced, and metal foils are widely used in various electronic technical fields, for example, printed wiring boards, battery negative electrode materials, and the like.
The surface of the existing metal foil product generally needs to be roughened so as to have good adhesion with an application carrier, such as a circuit board substrate and the like, and the existing metal foil product is not easy to fall off when being used. However, in the case of the roughened surface of the conventional metal foil, metal nodules (aggregates of crystal grains formed by aggregation of two or more crystal grains in the microscopic morphology) are present in many cases, and the distribution is not uniform and the morphology is not uniform. If the local aggregation is more or larger, the local stress concentration of the metal layer is caused, the metal foil is easier to tear at the aggregated position, the metal foil is broken and scrapped in the transportation and use processes, and the obtained metal foil with a rough surface structure still has poor adhesion and insufficient radial strength when being combined with application carriers such as a circuit board substrate and the like, even the metal foil is bent and broken in the pressing process, and the quality and the processing efficiency of the circuit board are seriously influenced. Moreover, after the metal foil is laminated on the circuit board substrate, circuit etching is required, and the etching rate of the metal nodules is different from that of the normal grains, so that uneven circuit etching or incomplete circuit etching can be caused, the circuit reject ratio is increased, and even a short circuit risk is caused. The crystal grain agglomeration with a reasonable structure is arranged on the roughened surface of the metal foil, so that the roughened surface and the circuit board substrate have better peel strength, the circuit can be completely etched after lamination, and the risk of short circuit of the circuit is reduced.
At present, there have been few studies on the structural design of the metal nodules on the roughened surface of the metal foil in the microstructure, and the problems of the best adhesion, the improvement of the radial strength, the great reduction of the incidence of the bending crack, and the like, which are brought about by the improvement of the structural design of the metal nodules. Therefore, the method obtains a suitable structural design of the metal tumor to improve the radial strength of the metal foil, reduce the risk of bending and cracking of the metal foil during pressing, simultaneously improve the peeling strength between the roughened surface of the metal foil and the substrate, facilitate the improvement of the uniformity of line etching in the subsequent processing technology, and reduce the risk of poor short circuit of the line etching, and is a problem to be solved urgently in the industry.
Disclosure of Invention
The embodiment of the invention aims to provide a metal foil and a printed circuit board, which effectively improve the quality of the metal foil and reduce the fraction defective of products applying the metal foil by optimizing the structure of metal nodules on the roughened surface of the metal foil.
In order to achieve the above object, an embodiment of the present invention provides a metal foil, which includes a roughened surface, wherein the roughened surface has a plurality of metal grains and a plurality of metal nodules, and the magnification of the roughened surface is 20000 times and the observation area is 420 μm 2 In the observation field of (2), the number X of the metal nodules satisfies X is less than or equal to 12, and the maximum diameter W of the metal nodules satisfies 0.1 mu m is less than or equal to W is less than or equal to 6 mu m.
As an improvement of the scheme, on the roughened surface, the maximum diameter of 0-67% of the metal tumors is more than or equal to 0.1 mu m and less than or equal to W and less than 1 mu m, the maximum diameter of 16.7-100% of the metal tumors is more than or equal to 1 mu m and less than or equal to W and less than or equal to 3 mu m, and the maximum diameter of 0-22% of the metal tumors is more than or equal to 3 mu m and less than or equal to W and less than or equal to 6 mu m; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
As an improvement of the scheme, on the roughened surface, 2% -40% of the metal tumors have the maximum diameter of 0.1 mu m-W < 1 mu m, 55% -85% of the metal tumors have the maximum diameter of 1 mu m-W < 3 mu m, and 0% -16% of the metal tumors have the maximum diameter of 3 mu m-W < 6 mu m; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
As an improvement of the proposal, the magnification of the scanning electron microscope is 20000 times, and the observation area is 420 μm 2 In the observation field of view of (2), the number X of the metal nodules satisfies X is less than or equal to 9.
In an improvement of the above aspect, a ratio of a maximum diameter of the metal nodules to a maximum diameter of the metal crystal grains on the roughened surface is a = 466/111.
As an improvement of the above aspect, the metal foil includes a conductive layer, and one surface of the conductive layer is the roughened surface.
As an improvement of the above scheme, the material of the conductive layer comprises at least one of copper, aluminum, zinc, nickel and silver metal elements and/or an alloy of at least one of the copper, aluminum, zinc, nickel and silver metal elements; and the thickness of the conductive layer is 1-5 μm.
As an improvement of the above scheme, the metal foil further includes a carrier layer, and the carrier layer is disposed on a surface of the conductive layer which is not the roughened surface.
As a refinement of the above solution, the material of the carrier layer includes at least one of the following metal elements: copper, aluminum and zinc, wherein the thickness of the carrier layer is 5-50 mu m; or the material of the carrier layer is an organic film, and the thickness of the carrier layer is 10-100 mu m.
As a refinement of the above, the metal foil further comprises a release layer, the release layer being disposed between the carrier layer and the conductive layer.
In the improvement of the scheme, the stripping layer is made of a metal material, and the thickness of the stripping layer is 2-100 nm; or the stripping layer is made of non-metal material, and the thickness of the stripping layer is less than or equal to 1 μm.
The embodiment of the invention also provides a printed circuit board, which comprises a circuit board substrate and the metal foil; and the roughened surface of the metal foil is in press fit with the circuit board substrate.
Compared with the prior art, the metal foil and the printed circuit board disclosed by the embodiment of the invention comprise the roughened surface, the roughened surface is provided with a plurality of metal grains and a plurality of metal nodules, the magnification of a scanning electron microscope is 20000 times, and the observation area is 420 mu m 2 In the observation field of (2), the number X of the metal nodules satisfies X is less than or equal to 12, and the maximum diameter W of the metal nodules satisfies 0.1 mu m is less than or equal to W is less than or equal to 6 mu m. By optimizing the maximum diameter and the number of the metal tumors on the roughened surface, the size and the number of the metal tumors on the roughened surface of the metal foil can be controlled within a reasonable range, crystal grains are uniformly distributed, the situation that the metal foil is broken and scrapped in the transportation and use processes due to the fact that the metal foils are easy to tear at the reunion position due to large size or large number of the metal tumors is effectively avoided, and the situations that the obtained metal foil with a rough surface structure still has poor adhesion and insufficient radial strength when being combined with application carriers such as a circuit board substrate and the like, and even the metal foil is bent and cracked in the pressing process are also effectively avoided. The metal foil structure provided by the embodiment of the invention can well improve the bonding performance of the metal foil and an application carrier, and reduce the phenomena of bending, deformation, cracking and the like of the metal foil in the bonding process. Moreover, the metal foil provided by the embodiment of the invention can meet the requirement of peel strength, is also suitable for manufacturing a packaging substrate and a fine circuit, and can be used as a packaging substrate material, because the surface crystal grains are uniform, the sizes of metal nodules are small, the number of the metal nodules is small, the packaging substrate and the metal foil can be tightly combined, a good line width and line distance can be kept after the circuit is etched, a line width part can be completely etched, the short circuit risk can be reduced, and the excellent rate of the circuit can be improved.
Drawings
FIG. 1 is a top electron micrograph of a first metal foil according to an embodiment of the present invention;
FIG. 2 is a schematic front view of a first metal foil according to an embodiment of the present invention;
FIG. 3 is a schematic top view of a first metal foil according to an embodiment of the present invention;
FIG. 4 is a schematic structural diagram of a second metal foil provided in an embodiment of the present invention;
FIG. 5 is a schematic structural diagram of a third metal foil provided in an embodiment of the present invention;
FIG. 6 is a schematic structural diagram of a fourth metal foil provided in an embodiment of the present invention;
FIG. 7 is a schematic structural diagram of a fifth metal foil provided in an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of a sixth metal foil provided in an embodiment of the present invention;
FIG. 9 is a schematic structural diagram of a seventh metal foil according to an embodiment of the present invention;
FIG. 10 is a schematic structural diagram of an eighth metal foil provided in an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a circuit board according to an embodiment of the present invention;
wherein, 1, roughening the surface; 11. a metal grain; 12. a metal tumor; 2. a conductive layer; 3. a carrier layer; 4. a peeling layer; 5. a bonding layer; 6. a first oxidation preventing layer; 7. a second oxidation preventing layer; 8. a resin layer; 9. a circuit board substrate.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In the description of the specification and claims, it is to be understood that the terms "upper", "lower", "left", "right", "front", "back", "top", "bottom", "inner", "outer", and the like, indicate orientations and positional relationships based on those shown in the drawings, are used for convenience in describing embodiments of the present invention, and do not indicate or imply that the referenced devices or components must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the embodiments of the present invention.
Furthermore, the terms first, second and the like in the description and in the claims, are used for descriptive purposes only to distinguish the same technical features, and are not to be construed as indicating or implying relative importance or implicit indication of the number of technical features indicated, nor is an order or temporal order necessarily described. The terms are interchangeable where appropriate. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature.
Example one
Referring to fig. 1 to 3, fig. 1 is a top-view electron microscope view of a first metal foil according to an embodiment of the present invention; FIG. 2 is a schematic front view of a first metal foil according to an embodiment of the present invention; fig. 3 is a schematic top view of a first metal foil according to an embodiment of the present invention. The embodiment of the invention provides a metal foil which comprises a roughened surface 1, wherein the roughened surface 1 is provided with a plurality of metal crystal grains 11 and a plurality of metal nodules 12, the magnification of a scanning electron microscope is 20000 times, and the observation area is 420 mu m 2 In the observation field of (2), the number X of the metal nodules satisfies X is less than or equal to 12, and the maximum diameter W of the metal nodules satisfies 0.1 mu m is less than or equal to W is less than or equal to 6 mu m.
The surface of the metal foil subjected to the roughening process is a roughened surface 1. The metal crystal grains 11 provided on the roughened surface 1 refer to projections formed on the respective surfaces of the metal foil subjected to the roughening treatment by the roughening treatment process. The metal nodules 12 are actually aggregates of grains formed by stacking, bonding, or agglomerating two or more metal grains 11 during growth. The shape or size parameters of the metal grains 11 or the metal nodules 12 on the roughened surface 1 of the metal foil according to the embodiment of the present invention include: the method for measuring parameters such as maximum diameter, maximum vertical height, quantity and the like is obtained by taking pictures of the surface morphology based on a scanning electron microscope and combining the statistics of measurement, statistics and analysis software. The specific method comprises the following steps:
(1) and (5) preparing a sample. Randomly cutting a sample with a certain size on the whole metal foil product, preparing the sample according to the detection requirement of a scanning electron microscope, observing the section and the surface appearance of the metal foil sample by selecting a proper multiple under the scanning electron microscope, and shooting a topography map.
(2) Repeating the above steps for multiple times to obtain multiple topographic maps, and performing statistics and analysis by means of statistics and analysis software.
In the embodiment of the present invention, referring to fig. 3, the maximum diameter W refers to the maximum value of the width or inner diameter of the metal tumor 12. On the roughened surface 1, a scanning electron microscope with magnification of 20000 times is used to form an observable area of 420 μm 2 And in an observation visual field with the width of 25.9 mu m, the number of the metal tumors 12 is that the foot X is less than or equal to 12, and the maximum diameter W is less than or equal to 0.1 mu m and less than or equal to 6 mu m.
By adopting the technical means of the embodiment of the invention, the maximum diameter W and the number X of the metal tumors 12 on the roughened surface 1 are optimized, the size and the number of the metal tumors 12 on the roughened surface of the metal foil can be controlled within a reasonable range, the crystal grains are uniformly distributed, the situation that the metal tumors 12 are large in size or large in number, the local stress concentration of the metal foil is caused, the metal foil is more easily torn at the position of agglomeration, and the metal foil is broken and scrapped in the transportation and use processes can be effectively avoided, and the situations that the obtained metal foil with a rough surface structure still has poor adhesion, insufficient radial strength, even bending and cracking of the metal foil in the pressing process and the like when the metal foil is combined with application carriers such as a circuit board substrate and the like can be effectively avoided. The metal foil structure provided by the embodiment of the invention can well improve the bonding performance of the metal foil and an application carrier, and reduce the phenomena of bending, deformation, cracking and the like of the metal foil in the bonding process. Moreover, the metal foil provided by the embodiment of the invention not only can meet the requirement of peeling strength, but also is suitable for manufacturing a packaging substrate and a fine circuit, and as the material of the packaging substrate, the metal foil has uniform surface crystal grains, small metal bump size and small quantity, the packaging substrate and the metal foil can be tightly combined, good line width and line distance can be kept after the circuit is etched, the line width part can be completely etched, the short circuit risk can be reduced, and the good rate of the circuit can be improved.
In a preferred embodiment, the roughened surface is formed to have an observable area of 420 μm at a magnification of 20000 times using a scanning electron microscope 2 And in an observation visual field with the width of 25.9 mu m, the number of the metal tumors 12 is that the foot X is less than or equal to 12, and the maximum diameter W is less than or equal to 1 mu m and less than or equal to 3 mu m.
In the embodiment of the invention, the maximum diameter W of the metal tumor 12 is further controlled within the range of 1-3 μm, so that the number of the metal tumor 12 is reasonable. And the size is not too large or too small but is in a reasonable range, so that the adhesion and the peel strength of the surface of the metal foil are further improved.
In another preferred embodiment, on the roughened surface, 0% -67% of the metal nodules have maximum diameters of 0.1 μm W < 1 μm, 16.7% -100% of the metal nodules have maximum diameters of 1 μm W < 3 μm, and 0% -22% of the metal nodules have maximum diameters of 3 μm W < 6 μm; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
More preferably, on the roughened surface, 2% -40% of the metal nodules have maximum diameters of 0.1 mu m W < 1 mu m, 55% -85% of the metal nodules have maximum diameters of 1 mu m W < 3 mu m, and 0% -16% of the metal nodules have maximum diameters of 3 mu m W < 6 mu m; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
In the embodiment of the present invention, the maximum diameter W of the metal nodules 12 on the roughened surface 1 and the ratio thereof are further optimized. Specifically, the width range of more metal nodules is set to be between 1 μm and 3 μm, the width range of a small part of metal nodules is set to be between 0.1 μm and less than 1 μm, the metal foil in the width range can assist in improving the roughness of the surface of the metal foil without causing excessive line transmission loss, the width range of the metal nodules in the smaller part is set to be between 3 μm and less than 6 μm, the metal foil in the width range can effectively improve the roughness of the surface of the metal foil, but too much line transmission loss is not caused, on the basis of the method, the maximum diameter W of 0% -67%, preferably 2% -40%, of the metal nodules 12 on the roughened surface 1 is set to be between 0.1 μm and 1 μm, the maximum diameter W of 16.7% -100%, preferably 55% -85%, of the metal nodules 12 is set to be between 1 μm and 3 μm, the maximum diameter W of the metal tumor 12 ranges from 0% to 22%, preferably from 0% to 16%, and is between 3 and 6 mu m. Due to the fact that the width of the metal tumor and the density distribution of the metal tumor with different widths have important influences on the properties of the coarsened surface, such as roughness, peeling strength, adhesion and the like, by limiting the range of the maximum diameter of the metal tumor 12 and limiting the proportion of the metal tumor 12 with different maximum diameters on the coarsened surface 1, the structure of the metal foil is optimized, and the properties of the coarsened surface are more reasonable, so that the coarsened surface of the metal foil is effectively improved, the adhesion property of the metal foil and an application carrier can be well improved, the phenomena of bending, deformation, cracking and the like of the metal foil in the adhesion process are reduced, and meanwhile, the risk that the local stress of the metal foil is too concentrated and is easily damaged in the transportation and all the time process is reduced. Moreover, the metal foil provided by the embodiment of the invention not only can meet the requirement of peeling strength, but also is suitable for manufacturing a packaging substrate and a fine circuit, and as the material of the packaging substrate, the metal foil has uniform surface crystal grains, small metal bump size and small quantity, the packaging substrate and the metal foil can be tightly combined, good line width and line distance can be kept after the circuit is etched, the line width part can be completely etched, the short circuit risk can be reduced, and the good rate of the circuit can be improved.
In a preferred embodiment, in addition to any of the above examples, the magnification of the scanning electron microscope is 20000 times and the observation area is 420 μm 2 In the observation field of view of (2), the number X of the metal nodules satisfies X is less than or equal to 9.
In the embodiment of the invention, the number X of the metal nodules in a unit area is further controlled, the number of the metal nodules 12 is less, the structure of the metal foil is optimized, crystal grains on the coarsened surface of the metal foil are more uniform, the size of the metal nodules is small, the number of the metal nodules is less, various performances of the coarsened surface are more reasonable, the quality of the metal foil is effectively improved, and the reject ratio of a product using the metal foil is reduced.
In a preferred embodiment, a ratio of a maximum diameter W of the metal nodules to a maximum diameter W' of the metal grains on the roughened surface is a = 466/111.
Referring to fig. 3, the maximum diameter W' of the metal crystal grain 11 refers to the maximum value of the width or diameter of the metal crystal grain 11. Since the size and distribution of the metal grains 11 on the roughened surface largely determine the properties such as roughness and adhesion of the metal foil, the metal nodules 12 are formed by the agglomeration of a plurality of metal grains 11 during the growth process, which results in the change of various properties of the metal foil. In the embodiment of the invention, the structural relationship between the metal crystal grains 11 and the metal tumors 12 on the roughened surface is considered, and the ratio a of the maximum diameters of the metal crystal grains 11 and the metal tumors 12 is optimized, so that the structure of the roughened surface of the metal foil is more reasonable, the bonding performance of the metal foil and an application carrier can be well improved, the phenomena of bending, deformation, cracking and the like of the metal foil in the bonding process are reduced, and meanwhile, the risk of breakage of the metal foil in the transportation and all the time process due to over-concentration of local stress is reduced. In application scenes such as manufacturing of a packaging substrate and a fine circuit, the packaging substrate and the metal foil can be tightly combined, good line width and line distance can be kept after the circuit is etched, the line width part can be completely etched, short circuit risks are reduced, and the line yield is improved.
In a preferred embodiment, in any of the above examples, the maximum vertical height of the metal nodules is 0.44 to 0.85 μm.
More preferably, the maximum vertical height of the metal tumor is 0.6-0.95 μm.
The maximum vertical height H refers to the maximum height of the metal tumor 12 in the vertical direction. In the embodiment of the invention, on the basis of optimizing the number and width dimensions of the metal nodules 12, the maximum vertical height of the metal nodules is further optimized, the metal nodules 12 meeting the number, the maximum diameter and the maximum vertical height range can enable the coarsening treatment surface of the manufactured metal foil to be more reasonable, various performances such as roughness, adhesiveness, peeling strength and the like can reach the optimal state, and the quality of the metal foil is effectively improved.
The radial tensile strength of the common metal foil and the metal foil with the structure of the embodiment of the invention, and the pressing wrinkle probability, the peeling strength and the rejection rate of the etched circuit after the same hot pressing condition are respectively tested by specific examples, wherein,
a represents a metal foil of the structure of the embodiment of the present invention, including metal foils a1, a2, and A3.
On the roughened surface of the metal foil A1, the number of metal nodules per unit observation area is 4, and 50% of the metal nodules have a maximum diameter satisfying 0.1 μm or more and W less than 1 μm, 50% of the metal nodules have a maximum diameter satisfying 1 μm or more and W less than 3 μm, and 0% of the metal nodules have a maximum diameter satisfying 3 μm or more and W less than 6 μm.
On the roughened surface of the metal foil A2, the number of metal nodules per unit observation area was 9, 44.4% of the metal nodules had maximum diameters satisfying 0.1 μm W < 1 μm, 33.4% of the metal nodules had maximum diameters satisfying 1 μm W < 3 μm, and 22.2% of the metal nodules had maximum diameters satisfying 3 μm W < 6 μm.
On the roughened surface of the metal foil A3, the number of metal nodules per unit observation area is 6, the maximum diameter of 66.6% of the metal nodules satisfies 0.1 [ mu ] m or more and W less than 1 [ mu ] m, the maximum diameter of 16.7% of the metal nodules satisfies 1 [ mu ] m or more and W less than 3 [ mu ] m, and the maximum diameter of 16.7% of the metal nodules satisfies 3 [ mu ] m or more and W or less than 6 [ mu ] m.
On the roughened surface of the metal foil A4, the number of metal nodules per unit observation area is 5, the maximum diameter of 0% of the metal nodules satisfies 0.1 μm or less and W is less than 1 μm, the maximum diameter of 100% of the metal nodules satisfies 1 μm or less and W is less than 3 μm, and the maximum diameter of 0% of the metal nodules satisfies 3 μm or less and W is less than 6 μm.
Specifically, as shown in table 1:
TABLE 1
Metal foil A of structure of embodiment of the invention Number of metal nodules X 0.1μm≤W＜1μm 1μm≤W＜3μm 3μm≤W≤6μm
Metal foil A1 4 50% 50% 0%
Metal foil A2 9 44.4% 33.4% 22.2%
Metal foil A3 6 66.6% 16.7% 16.7%
Metal foil A4 5 0% 100% 0%
B represents a common metal foil including metal foils B1 and B2.
On the roughened surface of the metal foil B1, the number of metal nodules per unit observation area is 13, and the maximum diameter W of the metal nodules is 3.5 μm or more and X is 6.8 μm or less.
The number of nodules per unit area observed on the roughened surface of metal foil B2 was 10, and the maximum diameter W of each nodule was greater than 6.2. mu.m.
By testing the radial tensile strength of the metal foil and the common metal foil with the structure of the embodiment of the invention, and the pressing wrinkle probability, the peeling strength and the rejection rate of the etched circuit under the same hot pressing condition, the data are shown in table 2:
TABLE 2
Product classification Radial tensile Strength (Mpa) Probability of press-fit wrinkles Peel strength (N/cm) from substrate Scrap rate of etched line
Metal foil A1 550 0.5% 10 0.5%
Metal foil A2 450 4% 6.5 3%
Metal foil A3 490 2% 7.8 1%
Metal foil A4 518 0.7% 8.3 0.6%
Common metal foil B1 400 6.2% 6 4.1%
Common metal foil B2 389 6.7% 5 4%
It can be seen that, on the roughened surface of the metal foil, the smaller the number of the metal nodules and the smaller the size, the greater the uniformity of the crystal grains, which indicates the greater the radial tensile strength of the metal foil, and that the greater the adhesion strength between the metal foil and the substrate after the hot press bonding process, the more difficult it is to peel off, and the smaller the probability of press-fitting wrinkles, the lower the rejection rate of the etched lines. After the metal foil is applied to a chip packaging substrate, a fine circuit or a high-frequency circuit board in subsequent process application, the wire width is better, the short circuit condition of the circuit is less, and the excellent rate is better.
The embodiment of the invention provides a metal foil, which optimizes the maximum diameter of metal nodules on a roughened surface, the number of the metal nodules in a unit observation area and the proportion of different metal nodules with the maximum diameter on the roughened surface, so that the properties of roughness, adhesiveness, peeling strength and the like of the roughened surface are more reasonable, the structure of the metal foil is improved, the situation that the metal foil is broken and scrapped in the transportation and use processes due to the fact that the metal nodules are large in size or large in number is effectively avoided, the situation that the metal foils are poor in adhesiveness and insufficient in radial strength when the obtained metal foil with the rough surface structure is combined with application carriers such as a circuit board substrate and the like can be effectively avoided, and even the situation that the metal foil is bent and cracked in the pressing process is generated. The metal foil structure provided by the embodiment of the invention can well improve the bonding performance of the metal foil and an application carrier, and reduce the phenomena of bending, deformation, cracking and the like of the metal foil in the bonding process. Moreover, the metal foil provided by the embodiment of the invention not only can meet the requirement of peeling strength, but also is suitable for manufacturing a packaging substrate and a fine circuit, and as the material of the packaging substrate, the metal foil has uniform surface crystal grains, small metal bump size and small quantity, the packaging substrate and the metal foil can be tightly combined, good line width and line distance can be kept after the circuit is etched, the line width part can be completely etched, the short circuit risk can be reduced, and the good rate of the circuit can be improved.
As a preferred embodiment, refer to fig. 4, which is a schematic structural diagram of a second metal foil provided in an embodiment of the present invention. The metal foil comprises a conductive layer 2, and one surface of the conductive layer 2 is the roughened surface 1.
In the embodiment of the present invention, the main structure of the metal foil includes the conductive layer 2, and in practical applications, for example, in the field of circuit boards, the conductive layer 2 is thermally pressed and bonded with a substrate of the circuit board, for example, in the field of batteries, the metal foil is used as a negative electrode material of the battery, and the conductive layer 2 is thermally pressed and bonded with a negative electrode active material in the negative electrode material. One surface of the conductive layer 2 for bonding with a substrate of a circuit board or a material such as a negative electrode active material is provided as the roughened surface 1, so that the adhesiveness of the conductive layer 2 is increased, and the occurrence of foaming, wrinkling, cracking and the like during bonding is reduced.
The conductive layer 2 is made of a metal having high conductivity and low resistivity. The conductive layer 2 comprises a single metal conductive layer and/or an alloy conductive layer; the single metal conducting layer is made of any one of copper, aluminum, zinc, nickel, silver and gold, the alloy conducting layer is made of any two or more of copper, aluminum, zinc, nickel, silver and gold, or any two or more of copper, aluminum, zinc, nickel, silver and gold and other materials in a mixed mode.
Preferably, the conductive layer 2 is an ultra-thin metal layer, and the thickness thereof is 1 to 5 μm.
In a specific implementation, the conductive layer 2 of the metal foil may be formed first, and then the metal grains 11 may be formed on the conductive layer 2 through another process. Of course, the conductive layer 2 of the metal foil and the metal crystal grains 11 may also be an integral structure formed by a one-step molding process. The material of the metal crystal grain 11 may be the same as or partially the same as or different from the material of the conductive layer 2, and is not limited herein.
As a preferred implementation manner, refer to fig. 5, which is a schematic structural diagram of a third metal foil provided in an embodiment of the present invention. The metal foil comprises a conductive layer 2 and a carrier layer 3, wherein the carrier layer 3 is arranged on one surface, which is not the roughened surface 1, of the conductive layer 2.
In the embodiment of the invention, the metal foil is of a multilayer structure and comprises a conductive layer 2 and a carrier layer 3 which are sequentially stacked, wherein one surface of the conductive layer 2 is a roughened surface 1, and the other surface is provided with the carrier layer 3.
The carrier layer 3 may be used to carry and protect the conductive layer 2, so that the conductive layer 2 is not damaged by external contact or collision, and after the metal foil and the circuit board are pressed at high temperature, the carrier layer 3 needs to be peeled off.
The carrier layer 3 is made of a metallic material or a non-metallic material. The metal material comprises at least one of metal elements such as copper, aluminum and zinc; the non-metallic material includes an organic thin film, etc. Since the carrier layer 3 mainly plays a role of carrying, a certain thickness is required, when the carrier layer 3 is a material having a metal element such as copper, aluminum or zinc, the thickness of the carrier layer is preferably 5-50 μm, more preferably 8-35 μm, such as 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 35 μm, etc., when the carrier layer is a non-metal material such as an organic film, the thickness of the carrier layer is preferably 10-100 μm, such as 10 μm, 15 μm, 18 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, etc., and the specific thickness of the carrier layer 3 can be set according to the actual use requirements, which will not be described in detail herein.
The carrier layer 3 is separated from the conductive layer 2 in a peelable removal manner or in a non-peelable removal manner. When the carrier layer 3 is removed in a non-peeling removal manner, such as: laser etching, chemical etching, grinding, plasma removal, and the like. When the carrier layer 3 is removed by peeling, the peeling means is, for example: manually peeled off and removed directly, or peeled off with the aid of a mechanical device.
Preferably, referring to fig. 6, it is a schematic structural diagram of a fourth metal foil provided in the embodiment of the present invention. The metal foil comprises a conductive layer 2 and a carrier layer 3, and further comprises a peeling layer 4, wherein the peeling layer 4 is arranged between the carrier layer 3 and the conductive layer 2. That is, the metal foil includes a carrier layer 3, a peeling layer 4, and a conductive layer 2, which are sequentially stacked, and a surface of the conductive layer 2 away from the peeling layer 4 is the roughened surface 1.
In the embodiment of the present invention, when the carrier layer 3 is removed by peeling, the peeling is: the separation of the carrier layer 3 from the conductive layer 2 is achieved by peeling off the release layer 4, i.e. by peeling off the release layer 4.
Simultaneously, because the existence of peel off layer, can block the metal migration between conducting layer 2 and the carrier layer 3, moreover, peel off layer 4 can cover or fill the surface of carrier layer 3 unevenness, makes conducting layer 2 that forms in another surface of peel off layer 4 more level and more smooth, even and compact, has reduced the emergence of pinhole, and then is favorable to the preparation of follow-up circuit.
Preferably, the peeling layer 4 is made of a metallic material or a non-metallic material. The metal material comprises any one or more of molybdenum, titanium and niobium; the non-metal material comprises silicon, graphite, organic polymer materials and the like, and when the stripping layer is made of the non-metal material, the stripping layer can be in a release layer form. The release layer comprises a silicon-free release agent release layer, a silicone oil release layer or a nitrogen release layer. The release layer may be formed by coating and drying a release agent, and in one embodiment, the release agent may include HDPE (high density polyethylene) and PMA (propylene glycol methyl ether acetate) solvent, and the like. When the two release agents are adopted, the mass ratio of HDPE to PMA is preferably (1-5) to 7. In another embodiment, the release agent may include a fluorine release agent and a solvent; wherein the volume ratio of the fluorine release agent to the solvent is preferably (5-30) to 1. It is understood that the above solvent is not particularly limited, and a release agent solvent, such as butanone, which is conventional in the art, may be used, and does not limit the present invention.
Preferably, when the material of the peeling layer 4 is a metal material, the thickness of the peeling layer is 2-100 nm; or, when the material of the peeling layer is a non-metal material, the thickness of the peeling layer is less than or equal to 1 μm. The specific thickness of the peeling layer 4 can be set according to the actual use requirement, and will not be further described herein.
By adopting the structural arrangement of the stripping layer in the embodiment of the invention, the proper adhesive strength can be ensured, and meanwhile, a certain adhesive capacity is also kept, so that the metal foil cannot be delaminated in the hot pressing process.
In a preferred embodiment, the carrier layer 3 and/or the release layer 4 are filled with a medium for absorbing heat in the metal foil. By adding the medium for absorbing heat, when the metal foil is hot-pressed on a circuit board substrate or used as a negative electrode material of a new energy battery and is hot-pressed and bonded with a negative electrode active material, the medium for absorbing heat can absorb heat, the heat of the bonding surface of the conductive layer 2 is reduced, and the occurrence of foaming, wrinkling, cracking and the like during metal foil bonding is further reduced.
Preferably, the medium for absorbing heat is filler particles. In the metal foil, the filler particles are filled in three ways: one is to fill the filler particles only in the carrier layer 3; secondly, only the peeling layer 4 is filled with filler particles; thirdly, filler particles are filled in both the carrier layer 3 and the peeling layer 4.
It is understood that the filler particles may be in clusters, icicles, stalactites, dendrimers, and the like, due to differences in processing means and parameters. In addition, the medium for absorbing heat in the embodiment of the present invention is not limited to the filler particles, and is not limited to the above shape, and any medium having a heat absorbing function and filled in the support layer or the release layer is within the scope of the present invention.
As a preferred embodiment, refer to fig. 7, which is a schematic structural diagram of a fifth metal foil provided in an embodiment of the present invention. The metal foil comprises a conductive layer 2, a carrier layer 3, a peeling layer 4 and an adhesive layer 5, wherein the adhesive layer 5 is arranged between the carrier layer 3 and the peeling layer 4. That is, the metal foil includes a carrier layer 3, an adhesive layer 5, a peeling layer 4, and a conductive layer 2, which are sequentially stacked, and a surface of the conductive layer 2 remote from the peeling layer 4 is the roughened surface 1.
In the embodiment of the invention, the bonding layer 5 is additionally arranged between the carrier layer 3 and the peeling layer 4, so that the bonding force between the carrier layer 3 and the peeling layer 4 is improved, the carrier layer 3 and the peeling layer 4 are not separated during peeling, the peeling force is increased, and the peeling effect can be effectively improved. Simultaneously, because the existence of tie coat 5 and peel ply 4, can cover the surface of carrier layer 3 unevenness, make the conducting layer 2 that forms in the peel ply 4 another side more level and smooth, even and compact, reduced the emergence of pinhole, be favorable to the preparation of follow-up circuit.
Preferably, the bonding layer may be a metallic bonding layer or a non-metallic bonding layer. When the metal bonding layer is formed by the metal bonding layer, the metal bonding layer is made of any one or more materials of copper, zinc, nickel, iron and manganese; or, the metal bonding layer is made of one of copper or zinc and one of nickel, iron and manganese. When the non-metal adhesive layer is used, the material is at least one selected from polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber or acrylate thermoplastic resin, phenolic, epoxy, thermoplastic polyimide, urethane, melamine or alkyd thermosetting resin, BT resin and ABF resin.
As a preferred embodiment, refer to fig. 8, which is a schematic structural diagram of a sixth metal foil provided in an embodiment of the present invention. The metal foil comprises a conductive layer 2, a carrier layer 3, a stripping layer 4 and a first anti-oxidation layer 6, wherein the first anti-oxidation layer 6 is arranged on one surface, close to the stripping layer 4, of the conductive layer 2. That is, the metal foil includes a carrier layer 3, a peeling layer 4, a first oxidation preventing layer 6, and a conductive layer 2, which are sequentially stacked, and a surface of the conductive layer 2 away from the peeling layer 4 is the roughened surface 1.
In the embodiment of the invention, the first anti-oxidation layer 6 is arranged between the stripping layer 4 and the conducting layer 2, so that the oxidation resistance of the conducting layer 2 can be improved, an oxidation film generated by oxidation of the conducting layer is prevented, the electric conduction and heat conduction effects are influenced, the number of pinholes on the surface of the metal foil is reduced, and the conducting integrity of an etched circuit after the metal foil is subsequently bonded on a circuit board substrate is ensured. Further, since the adhesion between the first oxidation preventing layer 6 and the peeling layer 4 is weak, the peeling effect can be improved.
Optionally, the first oxidation preventing layer is made of at least one of metals such as nickel, copper, chromium, zinc, and/or an alloy including at least one of them. Illustratively, the first oxidation preventing layer 6 is formed on the surface of the conductive layer 2 by a process including electroless plating, electroless micro-plating, and the like.
As a preferred embodiment, refer to fig. 9, which is a schematic structural diagram of a seventh metal foil according to an embodiment of the present invention. The metal foil comprises a conductive layer 2, a carrier layer 3, a stripping layer 4, a first anti-oxidation layer 6 and a second anti-oxidation layer 7, wherein the second anti-oxidation layer 7 is arranged on one surface, far away from the stripping layer 4, of the conductive layer 2. That is, the metal foil includes a carrier layer 3, a peeling layer 4, a first oxidation prevention layer 6, a conductive layer 2, and a second oxidation prevention layer 7, which are sequentially stacked, and a surface of the conductive layer 2 away from the peeling layer 4 is the roughened surface 1.
In the embodiment of the invention, the second oxidation prevention layer 7 is additionally arranged on the roughened surface 1 of the conductive layer 2, so that the oxidation resistance of the bonding surface of the conductive layer 2 and the circuit board substrate can be effectively protected, and the bonding performance of the conductive layer 2 and the substrate can be synergistically improved by selecting a proper material. The anti-oxidation layer is arranged on the roughening surface 1, so that firstly, the anti-oxidation layer can play a role in preventing oxidation, secondly, the anti-oxidation layer can play a role in fixing and protecting metal grains and metal tumors, and equivalently, the roughened surface is covered with a protective layer, and the metal grains and the metal tumors are also protected and are not easy to fall off. In addition, a coupling agent layer is generally provided on the roughened surface, and mainly functions to enhance adhesion to the substrate. In the embodiment of the invention, the contribution rate of the coupling agent layer to the peeling strength is 15-20%. Therefore, the coupling agent layer is provided, and can play a role of enhancing the adhesive force and increasing the peeling strength together with the roughened surface of the metal crystal grains and the metal nodules.
Optionally, the second oxidation preventing layer is made of at least one of metals such as nickel, copper, chromium, zinc, and/or an alloy of at least one of them. Illustratively, the second oxidation preventing layer 7 is formed on the roughened surface 1 of the conductive layer 2 by a process including electroless plating, electroless micro-plating, or the like.
As a preferred implementation manner, refer to fig. 10, which is a schematic structural diagram of an eighth metal foil provided in an embodiment of the present invention. The metal foil comprises a conductive layer 2, a carrier layer 3, a peeling layer 4 and a resin layer 8, wherein the resin layer 8 is arranged on one surface of the conductive layer 2 far away from the peeling layer 4. That is, the metal foil includes a carrier layer 3, a peeling layer 4, a conductive layer 2, and a resin layer 8, which are sequentially stacked, and a surface of the conductive layer 2 remote from the peeling layer 4 is the roughened surface 1.
In the embodiment of the invention, the resin layer 8 is additionally arranged on the roughened surface 1 of the conductive layer 2, namely, the resin layer 8 is arranged on the surface of the conductive layer 2 bonded with the circuit board substrate, so that the functions of oxidation resistance, moisture resistance, water resistance and the like can be achieved, and the bonding performance with the substrate can be improved.
The resin layer 8 is made of at least one of thermoplastic resin, thermosetting resin, BT resin and ABF value, wherein the thermoplastic resin comprises polystyrene, vinyl acetate, polyester, polyethylene, polyamide, rubber or acrylic thermoplastic resin; the thermosetting resin comprises phenolic, epoxy, thermoplastic polyimide, carbamate, melamine or alkyd thermosetting resin.
It should be noted that the structure of the metal foil provided in the embodiment of the present invention is not limited to the multilayer structure of the above embodiment, and in practical applications, other material layers and additional structures may be added according to requirements, which do not limit the present invention.
Example two
Fig. 11 is a schematic structural diagram of a printed circuit board according to an embodiment of the present invention. The embodiment of the invention provides a printed circuit board which comprises a circuit board substrate 9 and a metal foil provided in any one of the above embodiments. The roughened surface 1 of the metal foil is pressed with the circuit board substrate 9.
It should be noted that, the structure of the metal foil may refer to the structure of the metal foil described in any of the above embodiments, and details are not described herein.
By adopting the technical means of the embodiment of the invention, the structure of the metal tumor on the roughened surface of the metal foil is optimized, the structure of the roughened surface of the metal foil is improved, the requirement on peeling strength can be met, the method is also suitable for manufacturing a packaging substrate and a fine circuit, and as the material of the printed circuit board, the surface crystal grains are uniform, the size of the metal tumor is small, the quantity of the metal tumor is small, the substrate of the circuit board and the metal foil can be tightly combined, the good line width and line distance can be kept after the circuit is etched, the line width part can be completely etched, the short circuit risk can be favorably reduced, and the yield of the circuit is improved.
While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims (12)

1. The metal foil is characterized by comprising a roughened surface, wherein the roughened surface is provided with a plurality of metal crystal grains and a plurality of metal nodules, the magnification of a scanning electron microscope is 20000 times, and the observation area is 420 mu m 2 In the observation field of (2), the number X of the metal nodules satisfies X is less than or equal to 12, and the maximum diameter W of the metal nodules satisfies 0.1 mu m is less than or equal to W is less than or equal to 6 mu m.
2. The metal foil as claimed in claim 1, wherein 0% to 67% of the nodules have a maximum diameter of 0.1 μm W < 1 μm, 16.7% to 100% of the nodules have a maximum diameter of 1 μm W < 3 μm, and 0% to 22% of the nodules have a maximum diameter of 3 μm W < 6 μm; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
3. The metal foil as claimed in claim 2, wherein on the roughened surface, 2% to 40% of the metal nodules have a maximum diameter of 0.1 μm W < 1 μm, 55% to 85% of the metal nodules have a maximum diameter of 1 μm W < 3 μm, and 0% to 16% of the metal nodules have a maximum diameter of 3 μm W < 6 μm; wherein the sum of the percentages of the metal nodules within the three maximum diameter ranges is less than or equal to 100%.
4. The metal foil according to claim 1, wherein the magnification at a scanning electron microscope is 20000 times and the observation area is 420 μm 2 In the observation field of view of (2), the number X of the metal nodules satisfies X is less than or equal to 9.
5. The metal foil according to claim 1, wherein a ratio of a maximum diameter of the metal nodules to a maximum diameter of the metal grains on the roughened surface is a = 466/111.
6. The metal foil according to any one of claims 1 to 5, wherein the metal foil comprises a conductive layer, and one side of the conductive layer is the roughened surface.
7. The metal foil of claim 6, wherein the material of the conductive layer comprises at least one of the metal elements copper, aluminum, zinc, nickel, silver and/or an alloy of at least one of them; and the thickness of the conductive layer is 1-5 μm.
8. The metal foil of claim 6 further comprising a carrier layer disposed on a side of the conductive layer that is not the roughened surface.
9. A metal foil as claimed in claim 8, wherein the material of the carrier layer comprises at least one of the following metal elements: copper, aluminum and zinc, wherein the thickness of the carrier layer is 5-50 mu m; or the material of the carrier layer is an organic film, and the thickness of the carrier layer is 10-100 mu m.
10. The metal foil of claim 8, further comprising a release layer disposed between the carrier layer and the conductive layer.
11. The metal foil as claimed in claim 10, wherein the material of the peeling layer is a metal material, and in this case, the thickness of the peeling layer is 2 to 100 nm; or the stripping layer is made of non-metal material, and the thickness of the stripping layer is less than or equal to 1 μm.
12. A printed wiring board comprising a wiring board substrate and the metal foil according to any one of claims 1 to 11; and the coarsening surface of the metal foil is pressed with the circuit board substrate.
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Citations (5)

* Cited by examiner, † Cited by third party
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TW589412B (en) * 2003-07-30 2004-06-01 Pioneer Technology Engineering Granulation method for metal foil applied on the printed circuit board
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CN114603946A (en) * 2022-05-12 2022-06-10 广州方邦电子股份有限公司 Metal foil, copper-clad laminate, wiring board, semiconductor, negative electrode material, and battery

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US20110262764A1 (en) * 2008-11-25 2011-10-27 Jx Nippon Mining & Metals Corporation Copper Foil for Printed Circuit
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