Electrolytic copper foil with preferred orientation of (200) crystal face as well as manufacturing method and application of electrolytic copper foil

Abstract

The present invention relates to an electrolytic copper foil having a preferred orientation of a (200) crystal plane, a method for manufacturing the same, and an application thereof, in which the electrolytic copper foil before heat treatment has a crystal grain orientation ratio of 20% or less in the (200) crystal plane as measured by XRD analysis, and a crystal grain orientation ratio of less than 20% in a {001} crystal plane family as measured by EBSD analysis; the electrolytic copper foil after heat treatment has a crystal grain orientation ratio in the (200) crystal plane of 50% or more as measured by XRD analysis and a crystal grain orientation ratio in the {001} family of crystal planes of 20% or more as measured by EBSD analysis. And the heat treatment is heating at 200 DEG C for two hours. The electrolytic copper foil subjected to heat treatment has a microstructure similar to that of a rolled and annealed copper foil and shows excellent mechanical properties.

Description

Technical Field

[0001] The present invention relates to an electrolytic copper foil with a preferred orientation of (200) crystal plane after heat treatment, a manufacturing method thereof, and a flexible copper-clad plate, a printed circuit board and an electronic device made from the electrolytic copper foil. Background Art

[0002] Traditionally, copper foil can be divided into two categories: rolled and annealed copper foil (RA) and electrodeposited copper foil (ED). Rolled and annealed copper foil is made from copper sheet. Through a series of hot and cold rolling processes using rollers, combined with annealing and other procedures, the copper foil is gradually thinned to a thickness typically between 6 and 70 μm. Electrodeposited copper foil, on the other hand, is made from copper granules or copper wire. These are dissolved in a sulfuric acid solution to form a copper sulfate solution. Direct current is then used for electroplating, reducing the copper ions in the copper sulfate solution to copper atoms, which are then deposited on the cathode surface, resulting in a copper foil thickness between 6 and 70 μm. The aforementioned copper foil thicknesses of 6 to 70 μm represent only commonly used specifications. Other thicknesses can be easily adjusted by controlling the rolling process or adjusting the parameters of the electroplating process.

[0003] Although rolled annealed copper foil and electrolytic copper foil are manufactured using different methods, the chemical composition of the resulting copper foil (excluding the surface-treated portion) is virtually identical, with both being pure copper with a purity of at least 99.9%. However, the mechanical properties of rolled annealed copper foil, such as tensile strength, elongation, and bending resistance, differ significantly from those of electrolytic copper foil. This is primarily due to the difference in the microstructure of the grain arrangement of rolled annealed copper foil after heat treatment (e.g., baking, lamination, or coating with resin).

[0004] Whether it is rolled annealed copper foil or electrolytic copper foil, its grain structure is polycrystalline (with uneven grain sizes) and directional, and the microstructure or texture can be analyzed and measured using X-ray diffractometer (XRD) and electron backscatter diffraction (EBSD). Crystallographic planes are represented by three Miller indices, such as (hkl). Because XRD diffraction peaks are related to the distance, relative position, and number of atoms in the unit cell, according to the selection rule, the crystal planes represented by (hkl) as face-centered cubic (FCC) crystal structure must be all odd or all even. As a result, the crystal plane orientation distribution obtained by XRD analysis may include, but is not limited to, (200), (220), (111), (311), etc. EBSD signals are derived from the Kikuchi pattern generated by diffraction kinematics, so grain orientation is characterized by the {001}, {101}, and {111} planes. EBSD analysis has the advantage over XRD analysis in that it can measure smaller grain sizes. While the results of XRD and EBSD analysis vary, they both offer valuable insights into the preferred orientation and grain orientation distribution of electrolytic copper foil.

[0005] Although the chemical composition of rolled annealed copper foil and electrolytic copper foil is similar, the grain orientation distribution and grain size of these two types of copper foil after heat treatment are quite different, resulting in different mechanical properties (e.g., elongation, ductility) and electrical properties (e.g., volume resistivity, conductor loss). This also leads to the use of rolled annealed copper foil in some special applications. For example, rolled annealed copper foil with high elongation and high ductility is used in the manufacture of high-frequency and high-speed printed circuit boards to improve its thermal stability and avoid deformation and warping. However, due to the high price of rolled annealed copper foil, the use of electrolytic copper foil to manufacture printed circuit boards has the advantage of lower manufacturing costs.

[0006] Based on the above-mentioned shortcomings of rolled annealed copper foil and electrolytic copper foil, one object of the present invention is to provide an electrolytic copper foil with a preferred (200) crystal orientation. Another object of the present invention is to provide a method for manufacturing the electrolytic copper foil and its applications. The applications include flexible copper-clad laminates, printed circuit boards, and electronic devices made therefrom. Summary of the Invention

[0007] The present invention provides an electrolytic copper foil with a preferred orientation of (200) crystal plane after heat treatment, wherein The electrolytic copper foil before heat treatment has a grain orientation ratio of less than 20% in the (200) crystal plane as determined by XRD analysis, and a grain orientation ratio of less than 20% in the {001} crystal plane family as determined by EBSD analysis; The electrolytic copper foil after heat treatment has a grain orientation ratio of 50% or more in the (200) crystal plane as determined by XRD analysis, and a grain orientation ratio of 20% or more in the {001} crystal plane family as determined by EBSD analysis; and The heat treatment is performed at 200° C. for two hours.

[0008] The present invention also provides a method for manufacturing electrolytic copper foil, which comprises: i) providing an electrolyte having a temperature of 20° C. to 55° C. in the electrolytic cell; ii) At 30A / dm 2 Up to 100A / dm 2 A current density of 1000 Å is applied to an anode plate and a rotating cathode roller separated from each other in an electrolyte; iii) obtaining an electrolytic copper foil by electrodeposition on a rotating cathode roller; and iv) separating the electrolytic copper foil obtained in step iii); The electrolyte includes: 120g / L to 450g / L copper sulfate, 30g / L to 140g / L sulfuric acid. 0.01 ppm to 5.00 ppm of chloride ion, and 0.01 ppm to 2.50 ppm of at least one additive.

[0009] The present invention further provides a flexible copper-clad laminate, comprising: The electrolytic copper foil of the present invention or the electrolytic copper foil produced by the method of the present invention, and a dielectric layer disposed on at least one surface of the electrolytic copper foil; in The electrolytic copper foil has a grain orientation ratio of more than 50% in the (200) crystal plane as determined by XRD analysis; and a grain orientation ratio of more than 20% in the {001} crystal plane family as determined by EBSD analysis; The dielectric layer has a thickness of 5.0 μm to 100 μm; and The dielectric layer is composed of at least one layer of a polymer material having a thermal decomposition temperature (1%) of 260° C. or higher.

[0010] The present invention further provides a printed circuit board, which is made of the flexible copper clad laminate of the present invention.

[0011] The present invention further provides an electronic device comprising the printed circuit board of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 shows the grain orientation distribution of two copper foils obtained by XRD analysis of their M planes. The sample in Figure 1(A) is the rolled annealed copper foil of Comparative Example 1 of the present invention; the sample in Figure 1(B) is the electrolytic copper foil of Comparative Example 3 of the present invention.

[0013] Figure 2 shows grain size images of two copper foils obtained by EBSD analysis of their cross sections. The sample in Figure 2(A) is the rolled annealed copper foil of Comparative Example 1 of the present invention; the sample in Figure 2(B) is the electrolytic copper foil of Comparative Example 3 of the present invention.

[0014] Figure 3 One embodiment of the production process of the electrolytic copper foil of the present invention is shown.

[0015] FIG4 shows a specific embodiment of the electrolytic copper foil of the present invention, which is a grain orientation distribution diagram (A) obtained by XRD analysis of the sample of Example 6 of the present invention and a grain size photograph (B) obtained by EBSD analysis of its cross section. DETAILED DESCRIPTION

[0016] Unless otherwise indicated, all publications, patent applications, patents, and other references mentioned herein are expressly incorporated by reference in their entirety for all purposes as if fully set forth.

[0017] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one skilled in the art. In case of conflict, the present specification, including definitions, will control.

[0018] Unless otherwise indicated, all percentages, parts, ratios, etc. are by weight.

[0019] As used herein, the term "made from" is synonymous with "comprising." As used herein, the terms "comprises," "comprising," "includes," "including," "has," "having," "contain," or "containing" or any other variations thereof are intended to cover a non-exclusive inclusion. For example, a composition, process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition, process, method, article, or apparatus.

[0020] The transitional phrase "consisting of" excludes any unrecited element, step, or ingredient. If in a claim, the phrase renders the claim closed, excluding materials other than those recited, except for impurities normally associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim, rather than immediately following the preamble, it is limited only to the elements recited in that clause; other elements are not excluded from the claim as a whole.

[0021] The transitional phrase "consisting essentially of is used to qualify a composition, method, or apparatus that also includes materials, steps, features, components, or elements other than those literally discussed, provided that such additional materials, steps, features, components, or elements do not materially affect one or more of the basic and novel characteristics of the claimed invention. The term "consisting essentially of falls between "comprising" and "consisting of."

[0022] The term "comprising" is intended to include embodiments encompassed by the terms "consisting essentially of and "consisting of. Similarly, the term "consisting essentially of is intended to include embodiments encompassed by the term "consisting of.

[0023] When an amount, concentration, or other value or parameter is given as a range, a preferred range, or a series of upper preferred values ​​and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is disclosed separately. For example, when a range of "1 to 5" is listed, the listed range should be interpreted as including ranges such as "1 to 4", "1 to 3", "1-2", "1-2 and 4-5", "1-3 and 5". When a numerical range is listed herein, unless otherwise stated, the range is intended to include its endpoints, as well as all integers and fractions within the range.

[0024] Furthermore, unless expressly stated to the contrary, "or" refers to an inclusive "or" and not to an exclusive "or." For example, the condition A or B is satisfied by any of the following: A is true (or exists) and B is false (or does not exist), A is false (or does not exist) and B is true (or exists), and both A and B are true (or exist).

[0025] "Mol %" or "mole %" refers to mole percent.

[0026] When referring to the grain orientation ratio on a particular crystal plane or family of crystal planes, this means the proportion of the indicated particular crystal plane or family of crystal planes relative to the sum of all crystal planes.

[0027] A twin boundary is the boundary between two adjacent grains that exhibit certain symmetric features. In copper, twinning typically occurs at an angle of 60 degrees. When referring to the twin boundary ratio, this refers to the ratio of the total length of the twin boundaries to the total length of all grain boundaries.

[0028] The embodiments of the present invention as described in the Summary of the Invention include any other embodiments described herein, may be combined in any manner, and the descriptions of variables in the embodiments relate not only to the electrolytic copper foil of the present invention but also to a flexible copper clad laminate including the electrolytic copper foil.

[0029] The present invention is described in detail below.

[0030] The present invention provides an electrolytic copper foil having a preferred orientation of (200) crystal plane after heat treatment, wherein the electrolytic copper foil before heat treatment (i.e., untreated) has a grain orientation ratio of less than 20% in the (200) crystal plane as determined by XRD analysis, and has a grain orientation ratio of less than 20% in the {001} crystal plane family as determined by EBSD analysis; the electrolytic copper foil after heat treatment has a grain orientation ratio of more than 50% in the (200) crystal plane as determined by XRD analysis, and has a grain orientation ratio of more than 20% in the {001} crystal plane family as determined by EBSD analysis; and the heat treatment is performed at 200°C for two hours.

[0031] In one embodiment, the preferred orientation of the electrolytic copper foil of the present invention before heat treatment is the (111) crystal plane; the preferred orientation after heat treatment is the (200) crystal plane, and the grain orientation ratio of the (200) crystal plane is greater than 50%.

[0032] In the present disclosure, the electrolytic copper foil before heat treatment has a grain orientation ratio of less than 20% in the (200) crystal plane, as measured by XRD analysis, and in particular, 5% to 20%. For example, the grain orientation ratio in the (200) crystal plane before heat treatment may be 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, or 20%, or a range consisting of any two of the above values. In addition, the electrolytic copper foil before heat treatment has a grain orientation ratio in the {001} crystal plane family, as measured by EBSD analysis, and in particular, 5% to less than 20%. For example, the grain orientation ratio in the {001} crystal plane family before heat treatment may be 5%, 7.5%, 10%, 12.5%, 15%, 17.5%, or 19.5%, or a range consisting of any two of the above values.

[0033] In the present disclosure, the electrolytic copper foil of the present invention has a grain orientation ratio in the (200) crystal plane of 50% or more, or 55% or more, or 60% or more, particularly 50% to 90%, and more particularly 81% to 89%, as measured by XRD analysis after heat treatment. For example, the grain orientation ratio in the (200) crystal plane after heat treatment may be 50%, 55%, 60%, 65%, 70%, 75%, 80%, 81%, 89%, or 90%, or a range consisting of any two of the above values. In addition, the grain orientation ratio in the {001} crystal plane family of the electrolytic copper foil after heat treatment, as measured by EBSD analysis, is 20% or more, particularly 20% to 45%. For example, the grain orientation ratio of the {001} crystal plane family after heat treatment may be 20%, 25%, 30%, 35%, 40%, or 45%, or a range between any two of the above values.

[0034] In one embodiment, the average grain size of the electrolytic copper foil of the present invention before heat treatment is less than 1.0 μm, particularly 0.5 μm to less than 1.0 μm, more particularly 0.8 μm to less than 1.0 μm; and the average grain size is measured by EBSD analysis.

[0035] In one embodiment, the electrolytic copper foil of the present invention has a twin boundary ratio of 30% or less, particularly 20% to 30%, and more particularly 23% to 28% before heat treatment, and the twin boundary ratio is measured by EBSD analysis.

[0036] In one embodiment, the electrolytic copper foil of the present invention has an average grain size of 2.0 μm or more, or 2.5 μm or more, or 3.0 μm or more after heat treatment, particularly 2.0 μm to 5.5 μm, and more particularly 2.0 μm to 4.7 μm; and the average grain size is measured by EBSD analysis.

[0037] In one embodiment, the electrolytic copper foil of the present invention has a twin boundary ratio of 50% or more, or 55% or more, or 60% or more after heat treatment, particularly 50% to 85%, and more particularly 55% to 80%; and the twin boundary ratio is measured by EBSD analysis.

[0038] In one embodiment, the thickness of the electrolytic copper foil of the present invention is 3.0 μm to 300 μm, or 3.5 μm to 150 μm, or 4.5 μm to 75 μm, or 5.0 μm to 35 μm.

[0039] In one embodiment, the surface roughness (Sz) of the M-side of the electrolytic copper foil of the present invention before heat treatment is 3.0 μm or less, or 2.5 μm or less, or 2.0 μm or less, particularly 1.5 μm to 3 μm, and more particularly 2.0 μm to 2.8 μm. Furthermore, the applicants have discovered that the surface roughness of the M-side of the electrolytic copper foil of the present invention before and after heat treatment is similar, i.e., there is no significant difference.

[0040] In one embodiment, the elongation of the electrolytic copper foil of the present invention before heat treatment is less than 5%, or less than 4.5%, particularly 3% to 4.8%, and more particularly 3.5% to 4.5%.

[0041] In one embodiment, the electrolytic copper foil of the present invention has an elongation after heat treatment of 5% or more, or 6% or more, or 7% or more, particularly 5% to 18%, and more particularly 6.5% to 15%.

[0042] In one embodiment, the tensile strength of the electrolytic copper foil of the present invention after heat treatment is 15 Kgf / mm 2 Above, or 17Kgf / mm 2 Above, or 19Kgf / mm 2 above.

[0043] In one embodiment, the tensile strength of the electrolytic copper foil of the present invention after heat treatment is 25Kgf / mm 2 Below, or 24Kgf / mm 2 Below, or 23Kgf / mm 2 the following.

[0044] Another object of the present invention is to provide a method for producing the electrolytic copper foil of the present invention, characterized in that, under production conditions maintaining a high current density, suitable additives are selected and their amounts in the electrolyte are controlled, and various parameters in the electroplating step are adjusted to produce an electrolytic copper foil having a preferred orientation of (200) crystal plane after heat treatment. The method comprises: i) providing a prepared electrolyte having a temperature of 20° C. to 55° C. in an electrolytic cell; ii) At 30A / dm 2 Up to 100A / dm 2 The current density is applied to the anode plate (i.e., positive electrode) and the rotating cathode roller (i.e., negative electrode) separated from each other in the electrolyte; iii) obtaining an electrolytic copper foil by electrodeposition on a rotating cathode roller; and iv) separating the electrolytic copper foil obtained in step iii); The electrolyte includes: 120g / L to 450g / L copper sulfate, 30g / L to 140g / L sulfuric acid. 0.01 ppm to 5.00 ppm of chloride ion, and 0.01 ppm to 2.50 ppm of at least one additive.

[0045] Figure 3 FIG. 1 is a flow chart of an embodiment of the method according to the present invention. Figure 3 The method includes first performing step S100: providing a prepared electrolyte into an electrolytic cell; then performing step S200: applying direct current to the anode plate and the rotating cathode roller; then performing step S300: electrodepositing copper foil on the cathode roller; and finally performing step S400: separating the produced electrolytic copper foil. The electrodeposition control conditions include the temperature of the electrolyte and the current density of the applied direct current.

[0046] The resulting electrolytic copper foil has two surfaces. During the manufacturing process, the surface that contacts the roller is called the "roller side" of the copper foil; the opposite side, facing the electrolyte, is called the "deposition side." Typically, the "roller side" of the copper foil is the shiny side (S side), while the "deposition side" is the matte side (M side).

[0047] In the method of the present invention, the temperature of the electrolyte generally ranges from 20°C to 55°C, preferably from 30°C to 50°C.

[0048] In the method of the present invention, the current density of the direct current applied for the electrodeposition is 30A / dm 2 Up to 100A / dm 2 Usually at 60A / dm 2 , or 70A / dm 2 , or 80A / dm 2 Especially when the electrodeposition is at 60A / dm 2 When the process is carried out at a speed of 0.5 μm or greater, with the appropriate cathode roller speed, the yield of copper foil can reach more than 16 μm / min, which can meet the standards of industrial high-speed production.

[0049] In the method of the present invention, the electrolyte comprises copper sulfate, sulfuric acid, chloride ions and at least one additive. The copper sulfate (as a source of copper ions) and sulfuric acid in the electrolyte are commercially available from various sources and can be used without further purification.

[0050] In one embodiment, the content of copper sulfate in the electrolyte is 120 g / L to 450 g / L; or 180 g / L to 400 g / L; or 240 g / L to 350 g / L based on the total volume of the electrolyte.

[0051] In one embodiment, the content of sulfuric acid in the electrolyte is 30 g / L to 140 g / L; or 50 g / L to 130 g / L; or 70 g / L to 120 g / L based on the total volume of the electrolyte.

[0052] The chloride ion source may be copper chloride or hydrochloric acid.Chloride ion sources are commercially available and may be used without further purification.

[0053] In one embodiment, the chloride ion content in the electrolyte is 0.01 ppm to 5.00 ppm; or 0.05 ppm to 2.50 ppm; or 0.10 ppm to 1.00 ppm, based on the total weight of the electrolyte.

[0054] Suitable additives for the electrolyte include gelatin, glue, cellulose, nitrogen-containing cationic polymers, or combinations thereof. There are no particular restrictions on the additives used, as long as the resulting electrolytic copper foil exhibits a preferred (200) crystal orientation after heat treatment. The aforementioned additives may be used in combination of one or more, depending on the circumstances. In one embodiment, the additive is a nitrogen-containing cationic polymer.

[0055] In one embodiment, the additive is a nitrogen-containing cationic polymer, and the weight average molecular weight of the nitrogen-containing cationic polymer is 500 g / mol to 12,000 g / mol.

[0056] In another embodiment, the nitrogen-containing cationic polymer is the reaction product of a diamine of formula (I) or an imidazole of formula (II) and an epoxide of formula (III) or a diepoxide of formula (IV) in a 1:1 molar ratio: in R 1 、R 2 、R 3 and R 4 Each independently is H or C1-C3 alkyl; R 5 、R 6 、R 7 and R 8 are each independently H or C1-C6 alkyl, and R 7 and R 8 are optionally linked to each other to form a saturated ring; R 9 and R 10 Each independently is H or C1-C4 alkyl; R 11 is selected from C2-C8 alkylene, C5-C 10 Cycloalkylene and C1-C4 alkylene-C5-C10 a divalent linking group of cycloalkylene-C1-C4 alkylene, and optionally substituted with C1-C4 alkyl or hydroxy; A is selected from C2-C8 alkylene, C5-C 10 Cycloalkylene, C1-C4 alkylene-C5-C 10 Cycloalkylene-C1-C4 alkylene, C6-C 20 Arylene and C1-C4 alkylene-C6-C 20 Arylene-C1-C4 alkylene divalent linking group, and optionally C1-C4 alkyl or Hydroxyl substitution; Y is H or C1-C4 alkyl; X is a halogen; p, q and r are each independently an integer from 0 to 10; and n is an integer of 1 to 20.

[0057] In the method of the present invention, the content of the additive in the electrolyte will depend on the specific additive selected, the concentration of chloride ions in the electrolyte, and the applied current density. In the method of the present invention, the content of the additive in the electrolyte is typically 0.01 ppm to 2.50 ppm, based on the gross weight of the electrolyte.

[0058] In one embodiment, the content of the additive in the electrolyte is 0.01 ppm to 2.50 ppm; or 0.05 ppm to 1.50 ppm; or 0.10 ppm to 0.50 ppm, based on the total weight of the electrolyte.

[0059] In the method of the present invention, the electrolyte may further include one or more other additives, such as inhibitors or crystal orientation modifiers. These other additives may be used in combination, depending on the circumstances. Other additives are typically present in small amounts (i.e., less than 5 ppm) as long as they do not interfere with the functional properties of the electrolytic copper foil of the present invention.

[0060] The electrolytic copper foil obtained by the method of the present invention is called raw foil; after appropriate surface treatment, such as the common copper foil surface treatment process, including pickling, roughening, heat-resistant layer electroplating, anti-oxidation layer electroplating, silane treatment and other processes, it is suitable for the preparation of flexible copper clad laminates. Depending on the application of the copper foil, the above-mentioned surface treatment process can be applied to one or both sides of the raw foil. When the electrolytic copper foil is incorporated into a flexible copper clad laminate, the side of the copper foil contacting the dielectric layer is called the "laminated surface"; the opposite side of the "laminated surface" is called the "photoresistive surface". In order to increase the bonding strength between the copper foil and the dielectric layer, the above-mentioned surface treatment process, such as roughening (i.e., producing copper nodules by electroplating) or silane treatment, will be applied to at least the laminated surface of the copper foil. When the roughened copper nodules are attached to the M side of the raw foil, this copper foil is usually called forward copper foil. When the roughened copper nodules are attached to the S side of the raw foil, the electrolytic copper foil is called reverse copper foil.

[0061] Since the grain size and preferred grain orientation of the electrolytic copper foil of the present invention are related to the microstructure of the raw foil, the roughened copper nodules, whether attached to the S-surface or the M-surface, do not affect the excellent properties exhibited by the raw foil. Flexible copper clad laminate

[0062] Another object of the present invention is to provide a flexible copper clad laminate (FCCL), comprising: The electrolytic copper foil of the present invention or the electrolytic copper foil made by the method of the present invention, and the dielectric layer provided on at least one surface of the electrolytic copper foil; wherein The electrolytic copper foil has a grain orientation ratio of more than 50% on the (200) crystal plane as determined by XRD analysis; and a grain orientation ratio of more than 20% on the {001} crystal plane family as determined by EBSD analysis; The dielectric layer has a thickness of 5.0 μm to 100 μm; and The dielectric layer is composed of at least one layer of a polymer material having a thermal decomposition temperature (1%) of 260° C. or higher.

[0063] The flexible copper clad laminate of the present invention may be a single-sided FCCL or a double-sided FCCL.

[0064] In one embodiment of the present invention, the dielectric layer in the single-sided or double-sided FCCL of the present invention has a thickness of 5.0 μm to 100 μm, or 10 μm to 75 μm, or 15 μm to 60 μm, or 20 μm to 50 μm. Depending on the specific application of the flexible copper clad laminate of the present invention, the ratio of the thickness of the electrolytic copper foil to the thickness of the dielectric layer ranges from 2:1 to 1:10.

[0065] In one embodiment of the present invention, the S-surface of the electrolytic copper foil in the single-sided FCCL or double-sided FCCL of the present invention is in contact with the dielectric layer as a lamination surface, and the S-surface of the electrolytic copper foil is roughened.

[0066] The flexible copper clad laminate of the present invention is produced by the following method, which includes: providing the electrolytic copper foil of the present invention or the electrolytic copper foil produced by the method of the present invention; and coating or laminating at least one layer of polymer material or its precursor on at least one surface of the electrolytic copper foil to form a dielectric layer. The process temperature used in the above method can be as high as 260°C to 350°C; therefore, the polymer material used to constitute the dielectric layer needs to be able to withstand high temperatures for several hours. Suitable polymer materials have a thermal decomposition temperature (1%) of 260°C or higher, or 300°C or higher, or 340°C or higher.

[0067] In one embodiment, the dielectric layer included in the flexible copper clad laminate of the present invention is composed of at least one layer of polymer material, and the thermal decomposition temperature (1%) of the polymer material is above 260°C, or above 300°C, or above 340°C.

[0068] Those skilled in the art can select suitable polymer materials to form the dielectric layer in the flexible copper clad laminate of the present invention, which has the above-mentioned properties for the desired application. Suitable polymer materials include polyimide (PI), liquid crystal polymer or fluoropolymer, such as poly (tetrafluoroethylene). In one embodiment, the dielectric layer is composed of polyimide.

[0069] In one embodiment, in the flexible copper clad laminate of the present invention, the polymer material constituting the dielectric layer is polyimide, liquid crystal polymer or fluorine-containing polymer. polyimide

[0070] When dielectric layer is made of polyimide, the precursor of polyimide is corresponding polyamic acid, which can be prepared by any method well known to those skilled in the art. Step comprises adding diamine component and dianhydride component to solvent, mixing and stirring at a suitable temperature to obtain polyimide precursor, that is, polyamic acid. Polyimide precursor can be cast on base film, then baked at high temperature and solidified to provide polyimide film. When aforementioned base film is surface treated copper foil of the present invention, then can obtain single-sided copper clad laminate of the present invention.

[0071] Suitable diamine components may be aromatic diamines selected from the group consisting of p-phenylenediamine (PPD), m-phenylenediamine (MPD), 2,5-dimethyl-1,4-phenylenediamine (DPX), 2,4-diaminotoluene, 2,5-diaminotoluene, 2,6-diaminotoluene, trifluoromethyl-2,4-diaminobenzene, trifluoromethyl-3,5-diaminobenzene, 4,4'-diamino-biphenyl, 2,2'-dimethyl-4,4'- Diaminobenzidine, 3,3'-dimethyl-4,4'-diaminobenzidine, 2,2'-bis(trifluoromethyl)benzidine (TFMB), 2,2-bis-(4-aminophenyl)propane, 2,2'-bis(4-amino-phenyl)hexafluoropropane (6F diamine), 4,4'-diaminobenzophenone, 4,4'-diaminodiphenylmethane (MDA), 4,4'-diaminodiphenyl ether (ODA), 3,4'-diaminodiphenyl Phenyl ether, 4,4'-diaminobenzanilide, 2-methoxy-4,4'-diaminobenzanilide, 1,2-bis-(4-aminophenoxy)benzene, 1,3-bis-(4-aminophenoxy)benzene, 1,4-bis-(4-aminophenoxy)benzene, 1,2-bis-(3-aminophenoxy)benzene, 1,3-bis-(3-aminophenoxy)benzene, 1,4-bis-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)benzene oxy)-3-(3-aminophenoxy)benzene, 1-(4-aminophenoxy)-4-(3-aminophenoxy)benzene, 4,4'-bis(aminophenoxy)biphenyl (BAPB), 2,2-bis-(4-[4-aminophenoxy]phenyl)propane (BAPP), 4-amino-phenyl-3-aminobenzoate, 4-aminophenyl-4-amino-benzoate, and N,N-bis-(4-aminophenyl)aniline, and combinations thereof.

[0072] Suitable dianhydride components may be aromatic dianhydrides selected from the group consisting of pyromelitic dianhydride (PMDA), 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 2,2'-bis[4-(4-aminophenoxy)phenyl]tetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BT ... '-Benzophenone tetracarboxylic dianhydride, 2,3,3',4'-benzophenone tetracarboxylic dianhydride, bis-2,5-(3',4'-dicarboxy diphenyl ether), 4,4'-oxydiphthalic anhydride (ODPA), bis(3,4-dicarboxy-phenyl) sulfide dianhydride, bisphenol A dianhydride (BPADA), bisphenol S dianhydride, 2,2-bis-(3,4-dicarboxyphenyl) 1,1,1,3,3,3,-hexafluoropropane dianhydride (6FDA), and combinations thereof. Note that the dianhydride constituting the dianhydride component may be in the form of a dianhydride, or in the form of a tetraacid or diester acid halide. However, in some embodiments, the preferred dianhydride component is in the form of a dianhydride because it is generally more reactive than the corresponding acid or ester.

[0073] Examples of the solvent used for the polymerization of polyamic acid include dimethylacetamide, N-methylpyrrolidone, 2-butanone, diglyme, or xylene, and one or two or more solvents may be used in combination.

[0074] Commercially available low dielectric polyimide films suitable for use in the present invention include those from DuPont Electronics, Inc. APICAL from Kaneka Chemical TM 、Pixeo TM BP; or from Ube

[0075] The flexible copper clad laminate of the present invention can be manufactured by laminating a thermoplastic film composed of the above-mentioned polymer material onto at least one treated surface of a surface-treated copper foil. Alternatively, the flexible copper clad laminate of the present invention can be manufactured by applying a coating composition containing the above-mentioned polymer material or a precursor thereof to the treated surface of the surface-treated copper foil of the present invention. Depending on the selection of the polymer material forming the dielectric layer, the coating composition may contain a suitable solvent or solvent system. Any suitable preparation method that can be implemented by those skilled in the art can be used to form the dielectric layer.

[0076] The dielectric layer-forming coating composition can be applied by various coating methods well known in the art, including spray coating, curtain coating, knife over roll coating, air knife coating, slot die coating, direct gravure printing, reverse gravure printing, offset gravure printing, or roller coating.

[0077] Because thickness and physical properties can be easily controlled, the dielectric layer of the flexible copper-clad laminate of the present invention is preferably prepared by directly coating a polymer material containing a solution / dispersion medium. The dielectric layer can be formed from only a single layer, but considering the adhesion between the dielectric layer and the electrolytic copper foil of the present invention, it is preferably formed from multiple layers.

[0078] As mentioned above, the dielectric layer can be formed from a single layer or multiple layers. For single-sided FCCLs with a single polyimide layer, a polyimide precursor can be directly cast onto a surface-treated copper foil. For multi-layer polyimide layers, polyimide solutions of different compositions can be applied sequentially to a polyamic acid solution. When the polyimide dielectric layer is formed from multiple layers, two or more polyimide precursors of the same composition can be used.

[0079] In one embodiment, a double-sided FCCL having a multi-layer polyimide layer as a dielectric layer is formed by first forming a multi-layer polyimide layer, and then placing the multi-layer polyimide layer on the first and second surfaces of an electrolytic copper foil, and laminating them simultaneously or sequentially.

[0080] After coating, the solvent or solvent mixture can be removed by heating in an oven at a temperature in the range of 100° C. to 200° C. The temperature and duration of heating in the oven will depend on the solvent used and the thickness of the coating.

[0081] The process parameters such as temperature, pressure and time used to prepare the flexible copper clad laminate of the present invention generally depend on the material properties of the substrate and the preparation method. Those skilled in the art can determine appropriate process parameters accordingly.

[0082] In some embodiments, the flexible copper clad laminate of the present invention is made by lamination.

[0083] In some embodiments, lamination is performed at a temperature ranging from 200°C to 400°C, or from 300°C to 370°C; a pressure ranging from 0.5 MPa to 10.0 MPa, or from 1.0 MPa to 5.0 MPa; and a duration ranging from 30 minutes to 300 minutes, or from 60 minutes to 240 minutes.

[0084] Regardless of whether the dielectric layer of the flexible copper-clad laminate of the present invention is formed by coating or laminating, the above method includes a corresponding heating process. Therefore, the electrolytic copper foil of the present invention can be directly used in the manufacture of the flexible copper-clad laminate without prior heat treatment. In addition, the flexible copper-clad laminate of the present invention exhibits a similar grain size and grain orientation distribution to that of a flexible copper-clad laminate containing a rolled annealed copper foil, as compared to a flexible copper-clad laminate using a conventional electrolytic copper foil, because the electrolytic copper foil contained therein has a microstructure with a preferred orientation of the (200) crystal plane.

[0085] Furthermore, the flexible copper clad laminate of the present invention also has excellent heat resistance and is expected to withstand the soldering and reflow steps in the printed circuit manufacturing process. For example, the flexible copper clad laminate of the present invention can withstand heat treatment at temperatures of 260°C, 288°C, or even 320°C or higher for at least 30 seconds or longer without blistering or delamination. printed circuit boards

[0086] The flexible copper-clad laminate of the present invention can be patterned using known methods (such as subtractive photolithography or additive electroplating) to form a predetermined conductor pattern (i.e., a circuit) on the photoresist surface of the copper foil to produce a printed circuit board (PCB), wherein the printed circuit board is a flexible printed circuit board (FPCB) or a rigid-flexible printed circuit board (RFPCB). Because the manufacturing processes of FPCBs and RFPCBs are well known to those skilled in the art, their disclosure is omitted herein for the sake of brevity.

[0087] Flexible printed circuit boards or rigid-flexible printed circuit boards made from the flexible copper-clad laminates of the present invention can be assembled with other components, such as leads and vias, to form various electronic devices. These include computer peripherals, such as ribbon leads for hard drives; consumer devices, such as laptops, tablets, e-readers, portable gaming devices, portable media players, digital cameras, or mobile phones; wearable devices; smart home devices; healthcare devices; automotive electronics; manned and unmanned vehicles; and aviation equipment, such as drones, aircraft, or spacecraft.

[0088] Without further elaboration, it is believed that one skilled in the art can, using the preceding description, utilize the invention to its fullest extent. Therefore, the following examples should be construed as merely illustrative and not limiting of the present disclosure in any way. Example

[0089] The abbreviation "E" stands for "Example" and "CE" stands for "Comparative Example", and the numbers following each indicate the example in which the electrolytic copper foil was prepared / used. The examples and comparative examples were prepared and tested in a similar manner.

[0090] The following experiments demonstrate the effectiveness of the present invention, but the present invention is not limited to the following. The electrolyte ingredients, dosage and ratio, processing details, and other details may be appropriately modified without departing from the scope of the present invention. Therefore, the present invention should not be construed as being limited by the experiments described below. Material

[0091] Gelatin: purchased from Singapore Jero Biotech Co., Ltd., Taiwan Branch, model FL-FCC0.

[0092] NCP-A: Nitrogen-containing cationic polymer, available from DuPont Electronics under the trade name Copper Gleam TM T4, whose Mw is between 7,000 and 11,000.

[0093] NCP-B: Nitrogen-containing cationic polymer, available from DuPont Electronics under the trade name Copper Gleam TM T2, whose Mw is between 2,000 and 5,000.

[0094] NCP-C: Nitrogen-containing cationic polymer, available from DuPont Electronics under the trade name Copper Gleam TM T1, whose Mw is between 1,000 and 5,000.

[0095] NCP-D: Nitrogen-containing cationic polymer, available from DuPont Electronics under the trade name Copper Gleam TM T5, whose Mw is between 2,000 and 5,000.

[0096] NCP-E: Nitrogen-containing cationic polymer, available from DuPont Electronics under the trade name Copper Gleam TM T6, whose Mw is between 500 and 1,000.

[0097] HEC: hydroxyethyl cellulose, purchased from DAICEL.

[0098] Copper sulfate, sulfuric acid, hydrochloric acid, and the above compounds whose commercial sources were not indicated were purchased from Sigma-Aldrich.

[0099] Copper foil RA1: a rolled annealed copper foil purchased from Taishin copper & alumina technologies, Co., Ltd., with a nominal thickness of 12 μm and product model RA501.

[0100] Copper foil RA2: rolled annealed copper foil purchased from JX Metals Corporation, with a nominal thickness of 12 μm and product model BHM-HAV2.

[0101] Copper foil ED1: electrolytic copper foil purchased from Chang Chun Petrochemical Co. Ltd., with a nominal thickness of 12 μm and product model RTF2. Examples 1-8 and Comparative Examples 1-6

[0102] Example 1

[0103] A basic electrolyte solution containing 260 g / L copper sulfate, 100 g / L sulfuric acid, 0.1 ppm chloride ions, and 0.1 ppm gelatin as an additive was prepared. A rotating electrode apparatus with a titanium roller as the cathode (negative electrode) and a dimensionally stable anode (DSA) plate (positive electrode) and a DC power supply was used. The electrolyte was filled in the space between the cathode and the cathode, and then a current density of 60 A / dm was used. 2 The electrolyte temperature is 40°C, the cathode speed is 400 rpm, and the electroplating time is 45 seconds. An electrolytic copper foil with a thickness of 12 μm is directly formed on the surface of the titanium roller. After the electrodeposition is completed, the electrolytic copper foil is removed from the titanium roller and surface treated by immersing the electrolytic copper foil in a copper protective agent for 5 seconds. The copper protective agent is purchased from DuPont Chemical Co., Ltd. in Taiwan, China. The model is CUPROTEC. TM The electrolytic copper foil was then removed and dried with compressed air before undergoing subsequent testing. The test results are shown in Tables 1 and 2, respectively.

[0104] Examples 2-6

[0105] The same basic electrolyte as in Example 1 was prepared, containing 260 g / L copper sulfate, 100 g / L sulfuric acid, 0.1 ppm chloride ions, and 0.1 ppm additives; the additives used in each example are listed in Table 1 and Table 2. Then, using the same equipment and electrodeposition conditions as in Example 1, the current density was 60 A / dm 2 With an electrolyte temperature of 40°C and a cathode speed of 400 rpm, electroplating was performed for 45 seconds to form a 12μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the electrolytic copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent tests as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0106] Example 7

[0107] The same basic electrolyte as in Example 1 was prepared, containing 260 g / L copper sulfate, 100 g / L sulfuric acid, 0.1 ppm chloride ions, and 0.1 ppm NCP-A as additives. Then, the same equipment and electrodeposition conditions as in Example 1 were used to conduct the electroplating at a current density of 60 A / dm 2 The electroplating process was carried out for 780 seconds at an electrolyte temperature of 40°C and a cathode speed of 400 rpm, forming a 210 μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent testing as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0108] Example 8

[0109] The same basic electrolyte as in Example 1 was prepared, containing 260 g / L copper sulfate, 100 g / L sulfuric acid, 0.1 ppm chloride ions, and 0.1 ppm NCP-A as additives. Then, the same equipment and electrodeposition conditions as in Example 1 were used, with a current density of 80 A / dm 2 With an electrolyte temperature of 40°C and a cathode speed of 400 rpm, electroplating was performed for 34 seconds to form a 12μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the electrolytic copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent testing as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0110] Comparative Examples 1-3

[0111] Comparative Examples 1-3 used commercially available copper foils. The rolled and annealed copper foil in Comparative Example 1 was designated RA1, the rolled and annealed copper foil in Comparative Example 2 was designated RA2, and the electrolytic copper foil in Comparative Example 3 was designated ED1. The sampling method, testing instruments, measurement methods, and analysis methods were the same as those used for the samples in Examples 1-9. The test results are shown in Tables 1 and 2, respectively.

[0112] Comparative Example 4

[0113] The electrolyte used contained only 260 g / L copper sulfate and 100 g / L sulfuric acid, without chloride ions and additives. Then, the same equipment and electrodeposition conditions as in Experimental Example 1 were used to conduct the electroplating at a current density of 60 A / dm 2 With an electrolyte temperature of 40°C and a cathode speed of 400 rpm, electroplating was performed for 45 seconds to form a 12μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the electrolytic copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent tests as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0114] Comparative Example 5

[0115] The electrolyte used contained 260 g / L copper sulfate, 100 g / L sulfuric acid and 0.1 ppm chloride ion, but no additives. Then, the same equipment and electrodeposition conditions as in Experimental Example 1 were used at a current density of 60 A / dm 2 With an electrolyte temperature of 40°C and a cathode speed of 400 rpm, electroplating was performed for 45 seconds to form a 12μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the electrolytic copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent tests as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0116] Comparative Example 6

[0117] The electrolyte used contained 260 g / L copper sulfate, 100 g / L sulfuric acid, and 0.1 ppm NCP-A as an additive, but did not contain chloride ions. Then, the same equipment and electrodeposition conditions as in Experimental Example 1 were used at a current density of 60 A / dm 2 With an electrolyte temperature of 40°C and a cathode speed of 400 rpm, electroplating was performed for 45 seconds to form a 12μm thick electrolytic copper foil directly on the titanium roller surface. After electrodeposition, the electrolytic copper foil was removed from the titanium roller and subjected to the same surface treatment steps and subsequent tests as in Example 1. The test results are shown in Tables 1 and 2, respectively.

[0118] Details of each test method are described below. Test Method XRD analysis

[0119] Two samples (10 cm x 10 cm) were cut from the electrolytic copper foil produced in each example. One sample remained untreated (i.e., before heat treatment), while the other was placed in an oven at 200°C (atmospheric pressure, air) for 2 hours for heat treatment. XRD analysis was used to measure and calculate the grain orientation ratio and grain size distribution of each sample.

[0120] The sample S to be tested was placed facing the low background noise stage and the X-ray diffractometer (wavelength 200 nm) was used. ) with a LynxEye detector, the measurement conditions are a step size of 0.025 degrees per point, and a 2θ angle measurement of 40 degrees to 95 degrees to obtain diffraction data. The data is removed from the background noise using EVA software, and the diffraction intensities of the Miller indices (111), (200), (220), and (311) are taken, and the texture coefficient (T) is used as follows. c (hkl)) formula for calculation. T c (hkl)=[I(hkl) / I0(hkl)] / (1 / N)[∑N I(hkl) / I0(hkl)] (T c : texture coefficient; I: sample diffraction intensity; I0: reference diffraction intensity; N: number of Miller indices, reference material diffraction intensity (I0)). Get T c (111), T c (200), T c (220), T c (311), each T c The sum of (hkl) is used as the denominator, and each T c (hkl) is used as the numerator and multiplied by 100 to obtain the grain orientation ratio of the sample on each crystal plane, and the results of each embodiment and each comparative example are recorded in Table 1. EBSD analysis

[0121] Two samples (10 cm x 10 cm) were cut from the electrolytic copper foil produced in each example. One sample remained untreated (i.e., before heat treatment), while the other was placed in a 200°C oven (atmospheric pressure, air) for 2 hours for heat treatment. EBSD analysis was then performed, and the data were analyzed using software to provide values ​​for average grain size, twin boundary ratio, and grain orientation ratio.

[0122] The EBSD sample was first prepared by polishing with an ion milling cross-section polisher, placed in the SEM (JEOL-IT800SHL) chamber with a 50-degree pre-tilt holder, and then tilted 20 degrees. High current mode was used, with an accelerating voltage set to 15-20 kV. EBSD data were collected using an Oxford Symmetric EBSD detector. EBSD data collection parameters were set as follows: magnification 3000x, and a collection step size of 0.1 μm.

[0123] For grain size analysis, the EBSD data were loaded into the AZtecCrystal software and the special boundaries were set to the copper phase and the crystallographic axes / angles to <111> The software automatically outputs the grain size (equivalent circle diameter) and grain distribution. The equivalent circle diameter is used to calculate the average grain size, and grains smaller than 0.5 μm are considered errors introduced during scanning and excluded from the calculation to obtain the average grain size. The results for each example and comparative example are recorded in Table 2.

[0124] For the twin grain boundary ratio analysis, the EBSD data were loaded into the AZtecCrystal software and the output was selected as BandContrast+Special Grain Boundary Map. The parameters of the Special Grain Boundary Map were set as follows: minimum angle of 10°, copper phase, crystal axis / angle of <111> The twin boundary ratios of the embodiments and comparative examples are shown in Table 2.

[0125] For the grain orientation ratio of the {001} crystal plane family, EBSD data was loaded into AZtecCrystal software for Texture component analysis, with the output selected as the grain orientation ratio and inverse pole figure for the {001} crystal plane. Because the test samples were cross-sectional samples, 001 / / ND was set to indicate that the 001 direction was parallel to the Y1 direction (defined as red), 101 / / ND was set to indicate that the 101 direction was parallel to the Y1 direction (defined as green), and 111 / / ND was set to indicate that the 111 direction was parallel to the Y1 direction (defined as blue). The deviation angle was set to 20 degrees to achieve a larger area ratio. The results of each embodiment and comparative example are recorded in Table 1. Copper foil thickness

[0126] According to the standard method of IPC-TM-650 2.2.12, the copper foil before heat treatment was cut and the thickness of the copper foil was measured by weighing. surface roughness

[0127] Using a laser scanning microscope (Olympus, Model: OLS-5000) at 100x objective magnification and without any cutoff filter, the M-surface of the copper foil sample before heat treatment was examined in five areas. Roughness was measured at different points according to ISO 25178, and the measured data were averaged. Surface roughness Sz was defined as the sum of the 10 largest peak heights and the 10 largest valley depths within a defined area. Elongation and tensile strength

[0128] Two samples (5 cm x 15 cm) were cut from the electrolytic copper foil produced / used in each example. One sample remained untreated (i.e., before heat treatment), while the other was placed in a 200°C oven (atmospheric pressure, air) for 2 hours for heat treatment. Tensile strength and elongation were measured at room temperature using a SHIMADZU AGS-X tensile testing machine according to IPC-TM-6502.4.18B. The results for each example and comparative example are reported in Table 2.

[0129] Table 1 *“N” means “before heat treatment”, and “Y” means “after heat treatment”. *Grain orientation ratio values ​​in bold indicate the preferred orientation of the copper foil after heat treatment.

[0130] As shown in Table 1, the XRD grain orientation distribution data for the rolled annealed copper foils of Comparative Examples CE1 and CE2 each exhibited a preferred (220) crystal plane orientation before heat treatment, and a preferred (200) crystal plane orientation after heat treatment, with grain orientation ratios on the (200) plane exceeding 66% and 99%, respectively. The commercially available electrolytic copper foil of Comparative Example CE3 exhibited a preferred (220) crystal plane orientation before and after heat treatment. Although the preferred (200) crystal plane orientation of the electrolytic copper foils of Comparative Examples CE4, CE5, and CE6 after heat treatment was observed, their grain orientation ratios on the (200) plane were less than 50%. Compared to the electrolytic copper foils in Examples E1 to E8, each of which is a specific embodiment of the electrolytic copper foil of the present invention, after heat treatment, their preferred orientation is the (200) crystal plane, and their corresponding grain orientation ratios on the (200) crystal plane are all greater than 50%. Thus, it can be seen that after heat treatment, the electrolytic copper foil of the present invention has a preferred orientation similar to that of the rolled annealed copper foil, and its grain orientation ratio on the (200) crystal plane is greater than 50%.

[0131] The EBSD grain orientation data in Table 1 show that after heat treatment, the rolled annealed copper foils of Comparative Examples CE1 and CE2 have a grain orientation ratio in the {001} family of planes exceeding 20%. However, after heat treatment, the grain orientation ratio in the {001} family of the electrolytic copper foils of Comparative Examples CE3 to CE6 is less than 20%. In contrast, the grain orientation ratio in the {001} family of the electrolytic copper foils of Examples E1 to E8 all have a grain orientation ratio in the {001} family of planes exceeding 20%.

[0132] In summary, the electrolytic copper foil of the present invention, after heat treatment, has a characteristic performance similar to that of the rolled annealed copper foil, with a preferred orientation of the (200) crystal plane; determined by XRD analysis, its grain orientation ratio on the (200) crystal plane is greater than 50%; determined by EBSD analysis, its grain orientation ratio in the {001} crystal plane family is greater than 20%.

[0133] Table 2 *“N” means “before heat treatment”, and “Y” means “after heat treatment”.

[0134] From the surface roughness (Sz) data in Table 2, it can be seen that the surface roughness (Sz) of the M side of the electrolytic copper foils of Examples E1 to E8 before heat treatment is 3.0 μm or less. In addition, comparing the conductivity data of Examples E1 to E8 and CE3, after heat treatment, the electrolytic copper foils of Examples E1 to E8 each have a surface roughness (Sz) of 57.0 x 10 6 S / m or above; the conductivity is better than the conductivity of commercial electrolytic copper foil of CE3 (55.20x 10 6 S / m), and the electrical conductivity is similar to that of the rolled annealed copper foil of CE2.

[0135] As can be seen from the data in Table 2, the average grain size of the electrolytic copper foils of Examples E1 to E8 before heat treatment is less than 1.0 μm; after heat treatment, the average grain size increases to more than 2.0 μm. In addition, the twin boundary ratio of the electrolytic copper foils of Examples E1 to E8 before heat treatment is less than 30%; after heat treatment, the twin boundary ratio increases to more than 50%. Furthermore, as can be seen from the data in Table 2, the electrolytic copper foils of Examples E1 to E8 have an elongation of more than 5% and a tensile strength of 15 kgf / mm after heat treatment. 2 Up to 25Kgf / mm 2 tensile strength.

[0136] Generally, the preferred orientation of the grain arrangement of the rolled annealed copper foil will significantly tend to the (200) crystal plane, and its grains will obviously grow to a size greater than 2.0 μm, see Figure 1 (A) and Figure 2 (A). Figure 1 (A) is the XRD grain orientation distribution diagram of the rolled annealed copper foil after heating at 200°C for two hours, which is the sample of Comparative Example 1 of the present invention. It can be clearly seen from Figure 1 (A) that the preferred orientation of the grain arrangement of the rolled annealed copper foil is the (200) crystal plane. Figure 2 (A) is an EBSD grain size photograph of the sample of Comparative Example 1. It can be clearly seen from the photograph of Figure 2 (A) and compared with its scale that the average grain size of the rolled annealed copper foil is at least greater than 2.0 μm, and the average grain size obtained by actual measurement is 4.56 μm.

[0137] In contrast, conventional electrolytic copper foil is typically electroplated using high current density, for example, direct current greater than 50 ASD, to achieve industrial mass production. However, under high current density conditions, the copper atoms in the copper plating layer easily grow along the loosely arranged (220) and / or (311) crystal planes. Even after heat treatment, the preferred orientation of the grain arrangement of the electrolytic copper foil is mostly (111) and / or (220) crystal planes rather than (200) crystal planes, and its grain size is relatively small, generally less than 2.0 μm. See Figures 1(B) and 2(B), which are samples of Comparative Example 3 of the present application.

[0138] In addition, the directional imaging inverse pole figure (hereinafter referred to as the inverse pole figure) obtained by EBSD analysis of the cross-section of the rolled annealed copper foil sample of Comparative Example 1 and the electrolytic copper foil sample of Comparative Example 3 was obtained. Comparing the grain size and grain orientation distribution of the rolled annealed copper foil and the electrolytic copper foil, the same conclusion can be drawn, that is, the grain size of the rolled annealed copper foil is significantly larger than the grain size of the electrolytic copper foil. In addition, the inverse pole figure of the rolled annealed copper foil sample shows that its main grain orientation is the {001} crystal plane family, which includes all crystal planes that are crystallographically equivalent, that is, including (001), (100) and (010) crystal planes; the inverse pole figure of the electrolytic copper foil sample shows that its main grain orientation is the {101} crystal plane family, including (101), (011) and (110) crystal planes.

[0139] Figure 4(A) and 4(B) Figures 2 and 3 show the grain orientation distribution obtained by XRD analysis of the ED copper foil of an example of the present application, as well as a grain size photograph of a cross-section of the copper foil obtained by EBSD analysis. The ED copper foil shown is a sample from Example 6 of the present application. Unlike the more conventional ED copper foil of Comparative Example 3, this ED copper foil has a grain arrangement with a preferred orientation of the (200) plane and significantly larger grain sizes. The inverse pole figure of the ED copper foil of Example 6 shows that its primary grain orientation is in the {001} plane family, similar to the results of the RA copper foil sample from Comparative Example 1.

[0140] Although the present invention has been illustrated and described in terms of typical embodiments, it is not intended to be limited to the details shown, as various modifications and substitutions are possible without departing from the spirit of the invention. Therefore, modifications and equivalents of the invention disclosed herein will occur to those skilled in the art using only routine experimentation, and all such modifications and equivalents are considered to be within the spirit and scope of the invention as defined by the claims.

Claims

1. An electrolytic copper foil having a preferred orientation of (200) crystal plane after heat treatment, wherein The electrolytic copper foil before heat treatment has a grain orientation ratio of less than 20% in the (200) crystal plane as determined by XRD analysis, and a grain orientation ratio of less than 20% in the {001} crystal plane family as determined by EBSD analysis; The electrolytic copper foil after heat treatment has a grain orientation ratio of 50% or more in the (200) crystal plane as determined by XRD analysis, and a grain orientation ratio of 20% or more in the {001} crystal plane family as determined by EBSD analysis; and The heat treatment is performed at 200° C. for two hours.

2. The electrolytic copper foil according to claim 1, wherein The electrolytic copper foil before heat treatment has an average grain size of less than 1.0 μm and a twin grain boundary ratio of less than 30%; The electrolytic copper foil after heat treatment has an average grain size of 2.0 μm or more and a twin grain boundary ratio of 50% or more; and The average grain size and twin boundary ratio are determined by EBSD analysis. 3 . The electrolytic copper foil according to claim 1 , wherein the thickness of the electrolytic copper foil is 3.0 μm to 300 μm.

4. The electrolytic copper foil according to claim 1, wherein The surface roughness Sz of the M surface of the electrolytic copper foil before heat treatment is 3.0 μm or less.

5. The electrolytic copper foil according to claim 1, wherein the electrolytic copper foil after heat treatment has a thickness of 57.0 x 10 6 Conductivity above S / m.

6. The electrolytic copper foil according to claim 1, wherein The electrolytic copper foil before heat treatment has an elongation of less than 5%; and The electrolytic copper foil after heat treatment has an elongation of more than 5% and a strength of 15Kgf / mm 2 Up to 25Kgf / mm 2 tensile strength.

7. A method for manufacturing the electrolytic copper foil according to claim 1, comprising: i) providing an electrolyte having a temperature of 20° C. to 55° C. in the electrolytic cell; ii) At 30A / dm 2 Up to 100A / dm 2 A current density of 1000 Å is applied to an anode plate and a rotating cathode roller separated from each other in an electrolyte; iii) obtaining an electrolytic copper foil by electrodeposition on a rotating cathode roller; as well as iv) separating the electrolytic copper foil obtained in step iii); Wherein, the electrolyte comprises: 120g / L to 450g / L copper sulfate, 30g / L to 140g / L sulfuric acid. 0.01 ppm to 5.00 ppm of chloride ion, and 0.01 ppm to 2.50 ppm of at least one additive.

8. The method of claim 7, wherein the additive comprises gelatin, glue, cellulose, a nitrogen-containing cationic polymer, or a combination thereof. 9 . The method according to claim 7 , wherein the additive is a nitrogen-containing cationic polymer, and the weight average molecular weight of the nitrogen-containing cationic polymer is 500 g / mol to 12,000 g / mol.

10. The method according to claim 9, wherein the nitrogen-containing cationic polymer is a reaction product of a diamine of formula (I) or an imidazole of formula (II) and an epoxide of formula (III) or a diepoxide of formula (IV) in a 1:1 molar ratio: in R 1 、R 2 、R 3 and R 4 Each independently is H or C1-C3 alkyl; R 5 、R 6 、R 7 and R 8 are each independently H or C1-C6 alkyl, and R 7 and R 8 are optionally linked to each other to form a saturated ring; R 9 and R 10 Each independently is H or C1-C4 alkyl; R 11 is selected from C2-C8 alkylene, C5-C 10 Cycloalkylene and C1-C4 alkylene-C5-C 10 a divalent linking group of cycloalkylene-C1-C4 alkylene, and optionally substituted with C1-C4 alkyl or hydroxy; A is selected from C2-C8 alkylene, C5-C 10 Cycloalkylene, C1-C4 alkylene-C5-C 10 Cycloalkylene-C1-C4 alkylene, C6-C 20 Arylene and C1-C4 alkylene-C6-C 20 a divalent linking group of arylene-C1-C4 alkylene, and optionally substituted with a C1-C4 alkyl group or a hydroxyl group; Y is H or C1-C4 alkyl; X is a halogen; p, q and r are each independently an integer from 0 to 10; and n is an integer of 1 to 20.

11. A flexible copper-clad laminate, comprising: The electrolytic copper foil according to claim 1, and a dielectric layer provided on at least one surface of the electrolytic copper foil; in The electrolytic copper foil has a grain orientation ratio of more than 50% in the (200) crystal plane as determined by XRD analysis; and a grain orientation ratio of more than 20% in the {001} crystal plane family as determined by EBSD analysis; The thickness of the dielectric layer is 5.0 μm to 100 μm; and The dielectric layer is composed of at least one layer of a polymer material having a thermal decomposition temperature (1%) of 260° C. or higher. 12 . The flexible copper clad laminate according to claim 11 , wherein the polymer material is polyimide, liquid crystal polymer or fluoropolymer.

13. A method for manufacturing the flexible copper clad laminate according to claim 11, comprising: Providing the electrolytic copper foil according to claim 1; as well as At least one layer of polymer material or a precursor thereof is coated or laminated on at least one surface of the electrolytic copper foil to form a dielectric layer.

14. A printed circuit board made of the flexible copper clad laminate according to claim 11, wherein the printed circuit board is a flexible printed circuit board or a rigid-flexible printed circuit board.

15. An electronic device comprising the printed circuit board according to claim 14.

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