CN117535741A - Electrolytic copper foil capable of being annealed at low temperature and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of electrolytic copper foil, and specifically discloses an electrolytic copper foil that can be annealed at low temperature and its preparation method and application. The preparation method of the electrolytic copper foil includes: reacting copper raw materials with dilute sulfuric acid to generate a copper sulfate solution, and filtering , add chloride ions and additives to obtain an electrolyte, conduct electrolysis to the electrolyte to obtain a raw foil; the additives include a leveling agent, a brightener and a moving agent; perform surface treatment on the raw foil to obtain a surface-treated raw foil; so The surface treatment includes at least one of pickling, roughening, curing, water washing, anti-oxidation, passivation and spraying silane; the surface-treated raw foil is subjected to two-stage annealing treatment to obtain an electrolytic copper foil that can be annealed at low temperature . This preparation process involves annealing at low temperatures, is short in time, and consumes little energy. The prepared electrolytic copper foil has high tensile strength, elongation, bending resistance and other properties, and can be used for processing FCCL in high-frequency and high-speed fields.

Description

Electrolytic copper foil that can be annealed at low temperature and its preparation method and application

Technical field

The invention belongs to the technical field of electrolytic copper foil, and specifically relates to an electrolytic copper foil that can be annealed at low temperature and its preparation method and application.

Background technique

Flexible Copper Clad Laminate (FCCL) is the processing substrate material of Flexible Printed Circuit Board (FPC). It is composed of flexible insulating base film and metal foil. Compared with rigid copper-clad laminates in terms of product characteristics, FCCL has the advantages of being thin, light, and bendable. The FPC produced has the characteristics of high wiring density, thinness, bendability, and three-dimensional assembly. FCCL has been widely used in aerospace equipment, military guidance systems, mobile phones, digital cameras, automotive satellite positioning devices, LCD TVs, notebook computers, wearable devices and other electronic products. Most metal foils used in FCCL are copper foils, including electrolytic copper foils and rolled copper foils. In recent years, with the improvement of electrolytic copper foil production technology, the bending resistance of electrolytic copper foil has been very close to that of rolled copper foil of the same specification. It can achieve high elongation and control the surface roughness within a specific range. Moreover, electrolytic copper foil has obvious advantages in terms of price. More and more FCCL manufacturers are beginning to use electrolytic copper foil instead of rolled copper foil.

The high speed/high frequency of signals means that signal transmission is increasingly concentrated on the "surface" of wires (called the skin effect). For example, when the frequency reaches 1GHz, the signal transmission thickness on the surface of the wire is only 2.1μm; when the signal transmission frequency When increasing to 10GHz, the signal transmission thickness on the conductor surface is 0.70μm. If high-speed FPC continues to use electrolytic copper foil with conventional roughness, the result will be: as the signal transmission frequency increases, the signal "distortion" caused by the skin effect will become more and more serious. Therefore, the application of low-roughness electrolytic copper foil on current high-speed materials is becoming more and more widespread, and VLP grade electrolytic copper foil has become the standard.

In the existing technology, in order to make the electrolytic copper foil more suitable for FCCL in the high-frequency and high-speed field, the electrolytic copper foil needs to control the surface roughness of the electrolytic copper foil to be at the VLP level (processed surface roughness Rz ≤ 2.0 μm). Various methods are used to control the mechanical properties of electrolytic copper foil. For example, patent application CN115478305A discloses a method for preparing electrolytic copper foil for lithium-ion batteries with high bending resistance and its additives. The raw material components of the additives include diphenylsulfonimide, isinglass, polypropylene glycol, dextrin and Sodium dimethylformamidopropane sulfonate is used to improve the bending resistance of electrolytic copper foil. However, this technical solution will cause defects and impurities inside the electrolytic copper foil, resulting in excessive warpage of the electrolytic copper foil. Even fish scales may appear. Patent application CN106536791A discloses an electrolytic copper foil and a manufacturing method thereof, a current collector for lithium secondary batteries containing the electrolytic copper foil, and a lithium secondary battery. The electrolytic copper foil is obtained by subjecting the electrolytic copper foil to an annealing treatment ( Annealing at 190°C for 1 hour), thereby improving the elongation and bending resistance of the electrolytic copper foil. However, this process has a high annealing temperature, takes too long, and consumes too much energy.

Therefore, there is currently a need for a preparation process for electrolytic copper foil that can be annealed at low temperature, is short in time, consumes little energy, and has high tensile strength, elongation and bending resistance.

Contents of the invention

In view of the problems existing in the prior art, the present invention provides an electrolytic copper foil that can be annealed at low temperature and its preparation method and application. The preparation process of the electrolytic copper foil is short in time and energy consumption. The obtained electrolytic copper foil has High tensile strength, elongation and bending resistance.

In order to achieve the above objects, the technical solutions adopted by the present invention are as follows:

On the one hand, the present invention provides a method for preparing electrolytic copper foil that can be annealed at low temperature, including the following steps:

S1. Liquid preparation: react the copper raw material with dilute sulfuric acid to generate a copper sulfate solution;

S2. Electrolysis: After filtering the copper sulfate solution, add chloride ions and additives to obtain an electrolyte, electrolyze the electrolyte to produce foil, and obtain a foil; the additives include leveling agents, brighteners and moving agents;

S3. Surface treatment: Surface treatment is performed on the raw foil to obtain a surface-treated raw foil; the surface treatment includes at least one of pickling, roughening, curing, water washing, anti-oxidation, passivation and silane spraying;

S4. Annealing treatment: The surface-treated raw foil is subjected to two-stage annealing treatment to obtain the electrolytic copper foil that can be annealed at low temperature.

Preferably, the copper raw material in step S1 includes at least one of copper wire, copper rod, copper block and copper powder.

Preferably, the conditions for electrolytic foil production in step S2 are: current density is 60-62A/m ² , electrolyte flow rate is 30-35m ³ /h, and electrolyte temperature is 48-50°C.

Preferably, the total amount of additives in step S2 is 18-30 mg/L.

Preferably, the mass ratio of the leveling agent, brightening agent and moving agent in step S2 is 0.5-1:1:1-2.

Further preferably, the mass ratio of the leveling agent, brightening agent and positioning agent in step S2 is 0.8-1:1:1-2.

Most preferably, the mass ratio of the leveling agent, brightening agent and moving agent described in step S2 is 1:1:1.

Preferably, the leveling agent in step S2 is tetrahydrothiazolethione and/or polyethyleneimine; the brightening agent is hexyl benzylammonium salt, sodium polydisulfide propane sulfonate and sodium mercaptoimidazole propane sulfonate. At least one of the following; the moving agent is hydroxyethyl cellulose and/or polyethylene glycol.

Preferably, the viscosity of the hydroxyethyl cellulose in a 2 wt.% aqueous solution at 20° C. is 500 mPa.s.

Preferably, the molecular weight of polyethylene glycol is 4000-6000 Da; the molecular weight of polyethyleneimine is 4000-10000 Da.

Preferably, the concentration of the tetrahydrothiazolethione is 4.0-6.0 mg/L, the concentration of the polyethyleneimine is 2.0-4.0 mg/L, and the concentration of the hexyl benzylammonium salt is 1.5-2.5 mg /L, the concentration of the sodium polydisulfide propane sulfonate is 3.0-5.0 mg/L, the concentration of the sodium mercaptoimidazole propanesulfonate is 1.5-2.5 mg/L, and the concentration of the hydroxyethyl cellulose The concentration of polyethylene glycol is 3.0-5.0 mg/L, and the concentration of polyethylene glycol is 2.0-4.0 mg/L.

Preferably, the pickling conditions in step S3 are: acid concentration 140-150g/L, temperature 30-40°C; the solidification conditions in step S3 are: using solidifying liquid for three solidifications, the solidifying solution contains a concentration of 50-56g/L copper ions and 90-120g/L sulfuric acid, the temperature of the solidifying solution is 40-46°C.

Preferably, the roughening conditions in step S3 are: use a roughening liquid for three roughenings. During the first roughening, the roughening liquid contains copper ions with a concentration of 12-14g/L and a concentration of 120-130g/L. Sulfuric acid and sodium tungstate with a concentration of 60-80mg/L, the temperature of the roughening liquid is 30-35°C; during the second roughening, the roughening liquid contains copper ions with a concentration of 12-16g/L and a concentration of 120 -150g/L sulfuric acid, the temperature of the roughening liquid is 30-34°C; during the third roughening, the roughening liquid contains copper ions with a concentration of 12-16g/L and sulfuric acid with a concentration of 120-150g/L. The temperature of the liquid is 30-34℃.

Preferably, the water washing conditions in step S3 are: temperature 25-35°C, pH 6.8-7.2, and water is ultrapure water.

Preferably, the anti-oxidation conditions in step S3 are: use an anti-oxidation liquid for anti-oxidation treatment, and the anti-oxidation liquid contains nickel ions with a concentration of 1.5-2.5g/L and zinc with a concentration of 3.5-4.5g/L. The concentration of ions and K ₄ P ₂ O ₇ is 70-100g/L, the pH of the anti-oxidation solution is 10-11, and the temperature is 25-35°C.

Preferably, the passivation conditions in step S3 are: using a passivation liquid for passivation treatment, the passivation liquid contains chromium ions with a concentration of 2.0-2.5g/L and K with a concentration of 70-100g/L. ₄ P ₂ O ₇ , the pH of the passivation solution is 11-12, and the temperature is 25-35°C.

Preferably, the water needs to be washed three times: the first water washing is required after three curing treatments, the second water washing is performed after the anti-oxidation treatment, and the third water washing is performed after the passivation treatment.

Preferably, the conditions for spraying silane in step S3 are: spraying an organosilane coupling agent, the concentration of the organosilane coupling agent is 1.0-1.5g/L, the pH is 9-12, and the temperature is 25-35°C.

Preferably, the organosilane coupling agent includes but is not limited to ethoxysilane coupling agent, aminosilane coupling agent, methacrylic silane coupling agent, epoxy silane coupling agent, mercaptosilane coupling agent at least one of them.

Preferably, the conditions for the two-stage annealing treatment in step S4 are: the first stage annealing treatment is oven baking during the winding process of the electrolytic copper foil, the temperature is 130-140°C, and the time is 5-10 seconds; the second stage annealing treatment is The annealing treatment is to wind up the electrolytic copper foil and put it into the oven together with the winding reel to bake at a temperature of 60-80°C for 6-8 hours.

On the other hand, the present invention provides an electrolytic copper foil that can be annealed at low temperature, which is prepared by the above preparation method.

Preferably, the electrolytic copper foil contains copper ions with a concentration of 80-90 g/L, sulfuric acid with a concentration of 110-120 g/L, and chloride ions with a concentration of 1.0-1.5 mg/L.

The invention also provides an application of the above-mentioned electrolytic copper foil or the electrolytic copper foil prepared by the above-mentioned preparation method in a flexible copper-clad laminate.

Compared with the existing technology, the present invention has the following beneficial effects:

(1) The preparation process of the electrolytic copper foil in the present invention is annealed at low temperature, which is short in time and energy consumption;

(2) By regulating the types and proportions of raw foil additives, the present invention can provide electrolytic copper foil with fine and uniform crystallization, gentle contours, stable peaks, uniform copper nodules, and few internal defects and impurities; by regulating the coarse curing additives and The concentration of cupric acid is used to obtain a VLP-level roughness treatment surface on the surface of the electrolytic copper foil; and then through two-step low-temperature treatment, the stress inside the electrolytic copper foil is further released, so that the annealed electrolytic copper foil has higher tensile strength, elongation and With its properties such as bending resistance, it can be used for processing FCCL in high-frequency and high-speed fields.

Detailed ways

The present invention will be described below through specific embodiments to make the technical solutions of the present invention easier to understand and grasp. However, the present invention is not limited thereto. The described embodiments are only some of the embodiments of the present invention, not all of them.

The endpoints of ranges and any values disclosed herein are not limited to the precise range or value, but these ranges or values are to be understood to include values approaching such ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges. These values The scope shall be deemed to be specifically disclosed herein. As used herein, the singular forms "a," "an," and "the" include singular and plural referents unless the context clearly dictates otherwise. The recitation of numerical ranges by endpoints includes all numbers and fractions within the corresponding range and the recited endpoints.

Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts should fall within the scope of protection of the present invention. The experimental methods described in the following examples are conventional methods unless otherwise specified; the reagents and materials described can be obtained from commercial sources unless otherwise specified.

Embodiment 1 A method for preparing electrolytic copper foil that can be annealed at low temperature

Step 1. Liquid preparation: Add copper wire to a copper-melting tank, add pure water, oxygen and dilute sulfuric acid, stir, heat and react to generate a copper sulfate solution;

Step 2. Electrolysis: After filtering the copper sulfate solution generated in step 1 through a filter, transport it to a high-level tank, add chlorine ions and additives to obtain an electrolyte, and then transport the electrolyte to the electrolytic tank for electrolysis to produce foil. The electrolysis conditions are that the current density is 62A/m ² and the electrolyte flow rate is 30 m ³ /h.

The copper ion content in the electrolyte is 85g/L, the sulfuric acid content is 115g/L, the chloride ion content is 1.0mg/L, the total additive amount is 18mg/L, and the electrolyte temperature is 48°C.

The additives contain hexyl benzyl ammonium salt (PPNI), sodium polydisulfide propane sulfonate (SPS), sodium mercaptoimidazole propane sulfonate (MESS), hydroxyethyl cellulose (HEC), polyethylene glycol ( PEG), tetrahydrothiazolethione and polyethyleneimine in water. Among them, the PPNI, SPS and MESS are used as brighteners, the HEC and PEG are used as moving agents, and the tetrahydrothiazolethione and polyethyleneimine are used as leveling agents. The mass ratio of the leveling agent, brightening agent and positioning agent is 1:1:1.

The viscosity of the HEC in a 2wt.% aqueous solution at 20°C is 500 mPa.s, the molecular weight of PEG is 5000Da, and the molecular weight of polyethyleneimine is 6000Da.

The concentration of PPNI is 1.5 mg/L, the concentration of SPS is 3.0 mg/L, and the concentration of MESS is 1.5 mg/L; the concentration of HEC is 3.0 mg/L, and the concentration of PEG is 3.0 mg/L; tetrahydrothiazolethione The concentration of polyethylenimine is 4.0mg/L, and the concentration of polyethyleneimine is 2.0mg/L.

Step 3. Surface-treat the raw foil produced by the electrolysis process in Step 2:

(1) Pickling: The sulfuric acid concentration in the pickling tank is 145g/L, and the temperature is 35°C;

(2) Coarse 1: The roughening tank contains a roughening liquid. The copper ion concentration in the roughening liquid is 13g/L, the sulfuric acid concentration is 125g/L, the sodium tungstate concentration is 60mg/L, and the roughening liquid temperature is 32°C; Coarse 2: The copper ion concentration in the roughening tank is 13g/L, the sulfuric acid concentration is 130g/L, and the temperature is 32°C; Coarse 3: The copper ion concentration in the roughening tank is 14g/L, and the sulfuric acid concentration is 14g/L. 130g/L, temperature is 32℃;

(3) Curing 1: The concentration of copper ions in the solidification tank is 52g/L, the concentration of sulfuric acid is 100g/L, and the temperature is 42°C; Curing 2: The concentration of copper ions in the solidification tank is 52g/L, and the concentration of sulfuric acid is 100g/L. The temperature is 42°C; Curing 3: The copper ion concentration in the curing tank is 52g/L, the sulfuric acid concentration is 100g/L, and the temperature is 42°C;

(4) Water washing: use ultrapure water, temperature 30°C, pH 7.0;

(5) Anti-oxidation: The concentration of nickel in the anti-oxidation treatment tank is 2.0g/L, the concentration of zinc is 4.0g/L, the concentration of K ₄ P ₂ O ₇ is 80g/L, the pH value is 10, and the temperature is 30°C;

(6) Water washing: use ultrapure water, temperature 30°C, pH 7.0;

(7) Passivation: The chromium concentration in the passivation treatment tank is 2.2g/L, the K ₄ P ₂ O ₇ concentration is 80g/L, the pH is 11, and the temperature is 30°C.

(8) Water washing: use ultrapure water, temperature 30°C, pH 7.0;

(9) Silane spraying: The concentration of γ-glycidoxypropyltrimethoxysilane coupling agent is 1.2g/L, the pH is 10, and the temperature is 30°C.

Step 4. Annealing treatment: including 1-stage annealing and 2-stage annealing. The 1-stage annealing is the electrolytic copper foil being baked in the oven during the winding process. The baking temperature is 130°C and the time is 10 seconds. The 2-stage annealing is after the electrolytic copper foil is rolled up and put into the oven together with the winding reel. Medium baking, the baking temperature is 60° C. for 8 hours, and then cooled to room temperature in a natural state to obtain the electrolytic copper foil that can be annealed at low temperature.

Example 2 A method for preparing electrolytic copper foil that can be annealed at low temperature

Step 1. Liquid preparation: Add copper wire to a copper-melting tank, add pure water, oxygen and dilute sulfuric acid, stir, heat and react to generate a copper sulfate solution;

Step 2. Electrolysis: After filtering the copper sulfate solution generated in step 1 through a filter, transport it to a high-level tank, add chlorine ions and additives to obtain an electrolyte, and then transport the electrolyte to the electrolytic tank for electrolysis to produce foil. The electrolysis conditions are that the current density is 60A/m ² and the electrolyte flow rate is 32m ³ /h.

The copper ion content in the electrolyte is 80g/L, the sulfuric acid content is 110g/L, the chloride ion content is 1.0mg/L, the total additive amount is 30mg/L, and the electrolyte temperature is 50°C.

The additives contain hexyl benzyl ammonium salt (PPNI), sodium polydisulfide propane sulfonate (SPS), sodium mercaptoimidazole propane sulfonate (MESS), hydroxyethyl cellulose (HEC), polyethylene glycol ( PEG), tetrahydrothiazolethione and polyethyleneimine in water. Among them, the PPNI, SPS and MESS are used as brighteners, the HEC and PEG are used as moving agents, and the tetrahydrothiazolethione and polyethyleneimine are used as leveling agents. The mass ratio of the leveling agent, brightening agent and positioning agent is 0.8:1:2.

The viscosity of the HEC in a 2 wt.% aqueous solution at 20° C. is 500 mPa.s, the molecular weight of PEG is 6000 Da, and the molecular weight of polyethyleneimine is 10000 Da.

The concentration of PPNI is 2.5mg/L, the concentration of SPS is 5.0mg/L, and the concentration of MESS is 2.5mg/L; the concentration of HEC is 5.0mg/L, the concentration of PEG is 5.0mg/L; tetrahydrothiazolethione The concentration of polyethylenimine is 6.0mg/L, and the concentration of polyethyleneimine is 4.0mg/L.

Step 3. Surface-treat the raw foil produced by the electrolysis process in Step 2:

(1) Pickling: The sulfuric acid concentration in the pickling tank is 140g/L and the temperature is 40°C;

(2) Coarse 1: The roughening tank contains a roughening liquid. The copper ion concentration in the roughening liquid is 14g/L, the sulfuric acid concentration is 130g/L, the sodium tungstate concentration is 80mg/L, and the roughening liquid temperature is 35°C; Coarse 2: The copper ion concentration in the roughening tank is 16g/L, the sulfuric acid concentration is 150g/L, and the temperature is 30°C; Coarse 3: The copper ion concentration in the roughening tank is 16g/L, and the sulfuric acid concentration is 16g/L. 120g/L, temperature is 30℃;

(3) Curing 1: The copper ion concentration in the solidification tank is 56g/L, the sulfuric acid concentration is 90g/L, and the temperature is 46°C; Curing 2: The copper ion concentration in the solidification tank is 56g/L, and the sulfuric acid concentration is 90g/L. The temperature is 46°C; Curing 3: The copper ion concentration in the curing tank is 56g/L, the sulfuric acid concentration is 90g/L, and the temperature is 46°C;

(4) Water washing: use ultrapure water, temperature 25°C, pH 6.8;

(5) Anti-oxidation: The concentration of nickel in the anti-oxidation treatment tank is 1.5g/L, the concentration of zinc is 4.5g/L, the concentration of K ₄ P ₂ O ₇ is 100g/L, the pH value is 11, and the temperature is 25°C;

(6) Water washing: use ultrapure water, temperature 25°C, pH 6.8;

(7) Passivation: The chromium concentration in the passivation treatment tank is 2.5g/L, the K ₄ P ₂ O ₇ concentration is 70g/L, the pH is 12, and the temperature is 35°C.

(8) Water washing: use ultrapure water, temperature 25°C, pH 6.8;

(9) Silane spraying: The concentration of acetyltrimethoxysilane is 1.0g/L, the pH is 12, and the temperature is 35°C.

Step 4. Annealing treatment: including 1-stage annealing and 2-stage annealing. The 1-stage annealing is the electrolytic copper foil being baked in the oven during the winding process. The baking temperature is 140°C and the time is 5 seconds. The 2-stage annealing is after the electrolytic copper foil is rolled up and put into the oven together with the winding reel. Medium baking, the baking temperature is 80° C. for 6 hours, and then cooled to room temperature in a natural state to obtain the electrolytic copper foil that can be annealed at low temperature.

Embodiment 3 A method for preparing electrolytic copper foil that can be annealed at low temperature

Step 1. Liquid preparation: Add copper wire to a copper-melting tank, add pure water, oxygen and dilute sulfuric acid, stir, heat and react to generate a copper sulfate solution;

Step 2. Electrolysis: After filtering the copper sulfate solution generated in step 1 through a filter, transport it to a high-level tank, add chlorine ions and additives to obtain an electrolyte, and then transport the electrolyte to the electrolytic tank for electrolysis to produce foil. The electrolysis conditions are that the current density is 60A/m ² and the electrolyte flow rate is 35m ³ /h.

The copper ion content in the electrolyte is 90g/L, the sulfuric acid content is 120g/L, the chloride ion content is 1.5mg/L, the total additive amount is 18mg/L, and the electrolyte temperature is 48°C.

The additives contain hexyl benzyl ammonium salt (PPNI), sodium polydisulfide propane sulfonate (SPS), sodium mercaptoimidazole propane sulfonate (MESS), hydroxyethyl cellulose (HEC), polyethylene glycol ( PEG), tetrahydrothiazolethione and polyethyleneimine in water. Among them, the PPNI, SPS and MESS are used as brighteners, the HEC and PEG are used as moving agents, and the tetrahydrothiazolethione and polyethyleneimine are used as leveling agents. The mass ratio of the leveling agent, brightening agent and positioning agent is 0.5:1:2.

The viscosity of the HEC in a 2wt.% aqueous solution at 20°C is 500mPa.s, the molecular weight of PEG is 4000Da, and the molecular weight of polyethyleneimine is 4000Da.

The concentration of PPNI is 1.5 mg/L, the concentration of SPS is 3.0 mg/L, and the concentration of MESS is 1.5 mg/L; the concentration of HEC is 3.0 mg/L, and the concentration of PEG is 3.0 mg/L; tetrahydrothiazolethione The concentration of polyethylenimine is 4.0mg/L, and the concentration of polyethyleneimine is 2.0mg/L.

Step 3. Surface-treat the raw foil produced by the electrolysis process in Step 2:

(1) Pickling: The sulfuric acid concentration in the pickling tank is 150g/L, and the temperature is 30°C;

(2) Coarse 1: The roughening tank contains a roughening liquid. The copper ion concentration in the roughening liquid is 12g/L, the sulfuric acid concentration is 120g/L, the sodium tungstate concentration is 70mg/L, and the roughening liquid temperature is 30°C; Coarse 2: The copper ion concentration in the roughening tank is 12g/L, the sulfuric acid concentration is 120g/L, and the temperature is 34°C; Coarse 3: The copper ion concentration in the roughening tank is 12g/L, and the sulfuric acid concentration is 12g/L. 150g/L, temperature is 34℃;

(3) Curing 1: The concentration of copper ions in the solidification tank is 50g/L, the concentration of sulfuric acid is 120g/L, and the temperature is 40°C; Curing 2: The concentration of copper ions in the solidification tank is 50g/L, and the concentration of sulfuric acid is 120g/L. The temperature is 40°C; Curing 3: The copper ion concentration in the curing tank is 50g/L, the sulfuric acid concentration is 120g/L, and the temperature is 40°C;

(4) Water washing: use ultrapure water, temperature 35°C, pH 7.2;

(5) Anti-oxidation: The concentration of nickel in the anti-oxidation treatment tank is 2.5g/L, the concentration of zinc is 3.5g/L, the concentration of K ₄ P ₂ O ₇ is 70g/L, the pH value is 10, and the temperature is 35°C;

(6) Water washing: use ultrapure water, temperature 35°C, pH 7.2;

(7) Passivation: The chromium concentration in the passivation treatment tank is 2.0g/L, the K ₄ P ₂ O ₇ concentration is 100g/L, the pH is 11, and the temperature is 25°C.

(8) Water washing: use ultrapure water, temperature 35°C, pH 7.2;

(9) Silane spraying: The concentration of γ-aminopropyltriethoxysilane is 1.5g/L, the pH is 9, and the temperature is 25°C.

Step 4. Annealing treatment: including 1-stage annealing and 2-stage annealing. The 1-stage annealing is the electrolytic copper foil being baked in the oven during the winding process. The baking temperature is 135°C and the time is 10 seconds. The 2-stage annealing is after the electrolytic copper foil is rolled up and put into the oven together with the winding reel. Medium baking, the baking temperature is 70° C. for 7 hours, and then cooled to room temperature in a natural state to obtain the electrolytic copper foil that can be annealed at low temperature.

Comparative example 1

Compared with Example 1, the only difference is:

In step 2, the total amount of additives in the electrolyte is 24 mg/L, in which leveling agents, brighteners and moving agents are present in the electrolyte in a mass ratio of 2:3:2. The concentration of the brightening agent PPNI is 1.5 mg/L, the concentration of SPS is 3.0 mg/L, and the concentration of MESS is 1.5 mg/L; the concentration of the moving agent HEC is 4.0 mg/L, and the concentration of PEG is 4.0 mg/L; the concentration of the leveling agent tetrahydrothiazolethione is 4.0 mg/L, and the concentration of polyethyleneimine is 2.0 mg/L.

Other steps are the same as in Example 1.

Comparative example 2

Compared with Example 1, the only difference is:

In step 2, the concentration of PPNI in the electrolyte is 1.0 mg/L, the concentration of SPS is 4.0 mg/L, and the concentration of MESS is 1.0 mg/L; the concentration of HEC is 3.0 mg/L, and the concentration of PEG is The concentration is 3.0 mg/L; the concentration of tetrahydrothiazolethione is 3.0 mg/L, and the concentration of polyethyleneimine is 3.0 mg/L.

Other steps are the same as in Example 1.

Comparative example 3

Compared with Example 1, the only difference is:

In step 3, the concentration of sodium tungstate in the roughening process 1 is 100 mg/L.

In step 4, the 1-stage annealing is done by oven baking during the winding process of the electrolytic copper foil. The baking temperature is 150°C and the time is 5 seconds; the 2-stage annealing is done after the electrolytic copper foil is rolled up, together with the winding reel. Put it into an oven and bake it at a baking temperature of 100°C for 6 hours, and then cool it to room temperature in a natural state to obtain the electrolytic copper foil that can be annealed at low temperature.

Other steps are the same as in Example 1.

Effect example

The low-temperature annealable electrolytic copper foils obtained in Examples 1-3 and Comparative Examples 1-3 were tested in accordance with "GB-T 5230-2020 Electrolytic Copper Foil for Printed Boards", and the physical properties in the table below were obtained. It can be seen that the low-temperature annealable electrolytic copper foil of Examples 1-3 of the present invention has a tensile strength at room temperature ≥ 400MPa, an elongation at room temperature ≥ 10.0%, a tensile strength at high temperature ≥ 260MPa, and an elongation at high temperature ≥ 21.0%. Roughness Rz≤2.00μm, peel strength ≥0.80N/mm, folding resistance ≥3000 times. It meets the testing standards and can provide FCCL manufacturers with electrolytic copper foil raw materials with high elongation, high bending resistance and low warpage.

Table 1 Physical properties of electrolytic copper foil

Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, but does not limit the protection scope of the present invention. Simple modifications or equivalent substitutions of the technical solution of the present invention by those of ordinary skill in the art do not deviate from the scope of the present invention. The essence and scope of the technical solution of the invention.

Claims (10)

1. A method for preparing electrolytic copper foil that can be annealed at low temperature, which is characterized in that it includes the following steps: S1. Liquid preparation: react the copper raw material with dilute sulfuric acid to generate a copper sulfate solution; S2. Electrolysis: After filtering the copper sulfate solution, add chloride ions and additives to obtain an electrolyte, electrolyze the electrolyte to produce foil, and obtain a foil; the additives include leveling agents, brighteners and moving agents; S3. Surface treatment: Surface treatment is performed on the raw foil to obtain a surface-treated raw foil; the surface treatment includes at least one of pickling, roughening, curing, water washing, anti-oxidation, passivation and silane spraying; S4. Annealing treatment: perform two-stage annealing treatment on the surface-treated raw foil to obtain the electrolytic copper foil that can be annealed at low temperature; The mass ratio of the leveling agent, brightening agent and moving agent described in step S2 is 0.5-1:1:1-2, the leveling agent is tetrahydrothiazolethione and/or polyethyleneimine, and the brightening agent The agent is at least one of hexyl benzyl ammonium salt, sodium polydisulfide propane sulfonate and sodium mercaptoimidazole propane sulfonate, and the moving agent is hydroxyethyl cellulose and/or polyethylene glycol. 2. The preparation method according to claim 1, characterized in that: the copper raw material in step S1 includes at least one of copper wire, copper rod, copper block and copper powder. 3. The preparation method according to claim 1, characterized in that: the electrolyte in step S2 contains copper ions with a concentration of 80-90g/L, sulfuric acid with a concentration of 110-120g/L and a concentration of 1.0-1.5 mg/L chloride ions; the conditions for electrolytic foil production described in step S2 are: current density is 60-62A/m ² , electrolyte flow rate is 30-35m ³ /h, and electrolyte temperature is 48-50°C. 4. The preparation method according to claim 1, characterized in that: the molecular weight of the polyethylene glycol is 4000-6000Da; the molecular weight of the polyethyleneimine is 4000-10000Da; the concentration of the tetrahydrothiazolethione is 4.0-6.0 mg/L, the concentration of the polyethyleneimine is 2.0-4.0 mg/L, the concentration of the hexyl benzylammonium salt is 1.5-2.5 mg/L, and the polydisulfide dipropane sulfonic acid The concentration of sodium is 3.0-5.0 mg/L, the concentration of sodium mercaptoimidazole propanesulfonate is 1.5-2.5 mg/L, the concentration of hydroxyethyl cellulose is 3.0-5.0 mg/L, and the polyethylene The concentration of glycol is 2.0-4.0mg/L. 5. The preparation method according to claim 1, characterized in that: the pickling conditions in step S3 are: acid concentration 140-150g/L, temperature 30-40°C; The roughening conditions in step S3 are: use a roughening liquid for three roughenings. During the first roughening, the roughening liquid contains copper ions with a concentration of 12-14g/L, sulfuric acid with a concentration of 120-130g/L and Sodium tungstate with a concentration of 60-80mg/L, the temperature of the roughening liquid is 30-35°C; during the second roughening, the roughening liquid contains copper ions with a concentration of 12-16g/L and a concentration of 120-150g/ L of sulfuric acid, the temperature of the roughening liquid is 30-34°C; during the third roughening, the roughening liquid contains copper ions with a concentration of 12-16g/L and sulfuric acid with a concentration of 120-150g/L. The temperature is 30-34℃; The conditions for solidification in step S3 are: use a solidifying liquid for three solidifications. The solidifying liquid contains copper ions with a concentration of 50-56g/L and sulfuric acid with a concentration of 90-120g/L. The temperature of the solidifying liquid is 40-46°C. . 6. The preparation method according to claim 1, characterized in that: the water washing conditions in step S3 are: temperature 25-35°C, pH 6.8-7.2; the anti-oxidation conditions in step S3 are: using anti-oxidation The anti-oxidation liquid contains nickel ions with a concentration of 1.5-2.5g/L, zinc ions with a concentration of 3.5-4.5g/L and K ₄ P ₂ O ₇ with a concentration of 70-100g/L. , the pH of the anti-oxidation liquid is 10-11, and the temperature is 25-35°C. 7. The preparation method according to claim 1, characterized in that: the passivation conditions in step S3 are: using a passivation liquid for passivation treatment, and the passivation liquid contains a concentration of 2.0-2.5g/L Chromium ions and K ₄ P ₂ O ₇ with a concentration of 70-100g/L, the pH of the passivation solution is 11-12, and the temperature is 25-35°C; the conditions for spraying silane in step S3 are: spraying organic silane couple coupling agent, the concentration of the organosilane coupling agent is 1.0-1.5g/L, the pH is 9-12, and the temperature is 25-35°C. 8. The preparation method according to claim 1, characterized in that: the conditions of the two-stage annealing treatment in step S4 are: the temperature of the first-stage annealing treatment is 130-140°C, and the time is 5-10 seconds; The temperature of the segment annealing treatment is 60-80°C and the time is 6-8 hours. 9. An electrolytic copper foil that can be annealed at low temperature, characterized in that it is prepared by the preparation method described in any one of claims 1-8. 10. Application of the electrolytic copper foil according to claim 9 or the electrolytic copper foil prepared by the preparation method according to any one of claims 1 to 8 in flexible copper-clad laminates.