A highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil and its preparation method and application

Abstract

The present invention belongs to the technical field of copper foil for printed circuit boards, and discloses a highly corrosion-resistant, heat-resistant and peel-resistant electrolytic copper foil, and a preparation method and application thereof. The preparation of the highly corrosion-resistant, heat-resistant and peel-resistant electrolytic copper foil of the present invention includes the pretreatment of roughening and curing of the copper foil, the first electroplating of the copper foil obtained by the pretreatment in a first corrosion-resistant and heat-resistant liquid, and the second electroplating in a second corrosion-resistant and heat-resistant liquid. The corrosion resistance and heat resistance of the electrolytic copper foil are improved by the synergy of the plating layer of the first corrosion-resistant and heat-resistant liquid and the plating layer of the second corrosion-resistant and heat-resistant liquid. In this process, there is no need to add rare metals such as niobium and molybdenum, which reduces costs and avoids the problem of reduced peel strength of the electrolytic copper foil due to the lack of niobium and molybdenum. The electrolytic copper foil obtained by the present invention has high heat resistance, strong corrosion resistance and high peel strength, which can meet the application of higher performance printed circuit boards.

Description

Technical Field

[0001] The present invention relates to the technical field of copper foil for printed circuit boards, and in particular to an electrolytic copper foil with high corrosion resistance, heat resistance and peeling resistance, and a preparation method and application thereof. Background Art

[0002] With the rapid development of the electronic information industry, the performance requirements for electrolytic copper foil are gradually increasing. Electrolytic copper foil refers to a metal foil material produced by electrochemical deposition using cathode copper or copper wire as the main raw material. The copper material is dissolved to form a copper sulfate solution. Then, in a dedicated electrolysis device, under the action of direct current, the copper ions in the copper sulfate solution are reduced to copper at the cathode to form the raw foil. The foil is then subjected to surface treatments such as surface roughening, curing, and forming a heat-resistant layer, a corrosion-resistant layer, and an anti-oxidation layer. A key step is the surface treatment of the raw foil. Existing treatment methods mainly involve surface roughening, the installation of heat-resistant layers, and the application of corrosion-resistant layers.

[0003] At present, electrolytic copper foil has three main defects. First, the heat-resistant layer and corrosion-resistant layer of the electrolytic copper foil are two-layer structures, which are usually prone to peeling, affecting the practical application of the electrolytic copper foil. Second, in order to improve the peeling strength of the heat-resistant layer and the corrosion-resistant layer with the original foil, researchers usually use the method of adding rare metals such as niobium and molybdenum. This method causes the production cost to be too high, which is not conducive to large-scale promotion and application. For example, Chinese patent CN109056009A discloses a copper foil for printed circuit boards and its preparation method. The copper foil containing an ultra-thin copper alloy layer of Cu-Ti-Nb-Mo can not only solve the powder shedding phenomenon, but also provide good peeling strength and etching properties. However, the metals used are mostly rare metals and the cost is high; third, the corrosion resistance of the electrolytic copper foil cannot meet the requirements of higher performance, which is not conducive to the development of the electronic information industry. Therefore, there is an urgent need to develop an electrolytic copper foil with high corrosion resistance, heat resistance and peeling resistance in this field. Summary of the Invention

[0004] The purpose of the present invention is to provide a highly corrosion-resistant, heat-resistant and peel-resistant electrolytic copper foil and its preparation method and application, so as to solve the problems that the existing electrolytic copper foil is high in cost and its corrosion resistance, heat resistance and peel strength cannot meet the application of higher performance printed circuit boards.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] The present invention provides a method for preparing an electrolytic copper foil with high corrosion resistance, heat resistance and peeling resistance, comprising the following steps:

[0007] (1) Roughening and curing: The copper foil is placed in a roughening solution for roughening, and then the roughened copper foil is placed in a curing solution for curing to obtain a pretreated copper foil;

[0008] (2) Corrosion and heat resistant treatment: The pretreated copper foil is first placed in a first corrosion and heat resistant solution for the first electroplating, and then placed in a second corrosion and heat resistant solution for the second electroplating to obtain an electrolytic copper foil.

[0009] Preferably, in the roughening solution, Cu 2+ The concentration of is 10-15 g / L, the concentration of H2SO4 is 150-180 g / L, and the concentration of Zn 2+ The concentration is 1 to 4 g / L; the current density of the roughening is 70 to 80 A / dm 2 ; The coarsening time is 6 to 10 seconds.

[0010] Preferably, in the solidification liquid, Cu 2+ The concentration of H2SO4 is 20-25 g / L, the concentration of H2SO4 is 90-100 g / L; the curing current density is 40-50 A / dm 2 ; The curing time is 20 to 30 seconds.

[0011] Preferably, in the first corrosion-resistant and heat-resistant liquid, Sn 2+ The concentration of Zn is 20~30g / L, 2+ The concentration of is 5-10 g / L, the concentration of carbon nanotubes is 3.1-4.2 g / L, the concentration of titanium tetrachloride is 10-15 g / L, the concentration of potassium pyrophosphate is 70-80 g / L, and the concentration of additives is 20-30 mg / L.

[0012] Preferably, the additive is polyethylene glycol and / or dodecyl polyoxyethylene ether.

[0013] Preferably, the current density of the first electroplating is 15 to 20 A / dm 2 ; The time of the first electroplating is 60 to 120 seconds.

[0014] Preferably, in the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 90-120 g / L, Cr 3+ The concentration of Ni is 10-15 g / L. 2+ The concentration is 5~8g / L, Co 2+ The concentration is 3-5g / L.

[0015] Preferably, the current density of the second electroplating is 10-15 A / dm 2 ; The second electroplating time is 20 to 30 seconds.

[0016] The present invention also provides the electrolytic copper foil prepared by the method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil.

[0017] The present invention also provides application of the electrolytic copper foil in printed circuit boards.

[0018] It can be seen from the above technical solution that compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention performs corrosion and heat resistance treatment on the pretreated copper foil using a first corrosion-resistant and heat-resistant liquid and a second corrosion-resistant and heat-resistant liquid; wherein the carbon nanotubes contained in the first corrosion-resistant and heat-resistant liquid act as a skeleton, thereby improving the strength of the coating; the tin, zinc, and titanium contained in the first corrosion-resistant and heat-resistant liquid can improve the corrosion resistance and heat resistance of the coating. In addition, by controlling the current density and the electroplating time, the tin can be distributed on the surface of the coating in the form of crystals, thereby increasing the surface roughness of the coating of the first corrosion-resistant and heat-resistant liquid and further improving the bonding strength between the coating of the first corrosion-resistant and heat-resistant liquid and the coating of the second corrosion-resistant and heat-resistant liquid; only chromium, nickel, and cobalt are added to the second corrosion-resistant and heat-resistant liquid, thereby avoiding the addition of rare metals such as niobium and molybdenum, thereby reducing costs. At the same time, the coating of the first corrosion-resistant and heat-resistant liquid and the coating of the second corrosion-resistant and heat-resistant liquid work together to avoid the problem of reduced peeling strength of the electrolytic copper foil caused by not adding niobium and molybdenum. DETAILED DESCRIPTION

[0020] The present invention provides a method for preparing an electrolytic copper foil with high corrosion resistance, heat resistance and peeling resistance, comprising the following steps:

[0021] (1) Roughening and curing: The copper foil is placed in a roughening solution for roughening, and then the roughened copper foil is placed in a curing solution for curing to obtain a pretreated copper foil;

[0022] (2) Corrosion and heat resistant treatment: The pretreated copper foil is first placed in a first corrosion and heat resistant solution for the first electroplating, and then placed in a second corrosion and heat resistant solution for the second electroplating to obtain an electrolytic copper foil.

[0023] In the roughening solution of the present invention, Cu 2+ The concentration of Zn is preferably 10 to 15 g / L, more preferably 11 to 14 g / L, the concentration of H2SO4 is preferably 150 to 180 g / L, more preferably 160 to 170 g / L, 2+ The concentration of is preferably 1 to 4 g / L, more preferably 2 to 3 g / L; the current density of the roughening is preferably 70 to 80 A / dm 2 , more preferably 72 to 78 A / dm 2 The roughening time is preferably 6 to 10 seconds, more preferably 7 to 9 seconds.

[0024] In the solidifying solution of the present invention, Cu 2+ The concentration of H2SO4 is preferably 20-25 g / L, more preferably 21-24 g / L, the concentration of H2SO4 is preferably 90-100 g / L, more preferably 95-97 g / L; the curing current density is preferably 40-50 A / dm2 , more preferably 43 to 46 A / dm 2 ; The curing time is preferably 20 to 30 seconds, more preferably 22 to 28 seconds.

[0025] In the first corrosion-resistant and heat-resistant liquid of the present invention, Sn 2+ The concentration of Zn is preferably 20 to 30 g / L, more preferably 25 to 27 g / L. 2+ The concentration of is preferably 5-10 g / L, more preferably 6-8 g / L, the concentration of carbon nanotubes is preferably 3.1-4.2 g / L, more preferably 3.5-4 g / L, the concentration of titanium tetrachloride is preferably 10-15 g / L, more preferably 11-13 g / L, the concentration of potassium pyrophosphate is preferably 70-80 g / L, more preferably 71-75 g / L, and the concentration of additives is preferably 20-30 mg / L, more preferably 22-24 mg / L.

[0026] In the first corrosion-resistant and heat-resistant liquid of the present invention, the diameter of the carbon nanotubes is preferably 20 to 25 nm, and more preferably 21 to 24 nm.

[0027] In the present invention, the additive is preferably polyethylene glycol and / or dodecyl polyoxyethylene ether.

[0028] In the present invention, the current density of the first electroplating is preferably 15 to 20 A / dm 2 , more preferably 17 to 19 A / dm 2 The time of the first electroplating is preferably 60 to 120 seconds, more preferably 70 to 100 seconds.

[0029] In the second corrosion-resistant and heat-resistant liquid of the present invention, the concentration of potassium pyrophosphate is preferably 90 to 120 g / L, more preferably 100 to 110 g / L, and Cr 3+ The concentration of Ni is preferably 10 to 15 g / L, more preferably 11 to 13 g / L. 2+ The concentration of Co is preferably 5 to 8 g / L, more preferably 6 to 7 g / L; 2+ The concentration is preferably 3 to 5 g / L, more preferably 3.2 to 4.5 g / L.

[0030] In the present invention, the current density of the second electroplating is preferably 10 to 15 A / dm 2 , more preferably 11 to 14 A / dm 2 The second electroplating time is preferably 20 to 30 seconds, more preferably 25 to 28 seconds.

[0031] In the present invention, the solvent used in the roughening liquid, the solidifying liquid, the first corrosion-resistant and heat-resistant liquid, and the second corrosion-resistant and heat-resistant liquid is water.

[0032] In the present invention, after the second electroplating, the obtained copper foil is dried; the drying temperature is preferably 60-80° C., more preferably 70-75° C.; the drying time is preferably 30-50 min, more preferably 40-45 min.

[0033] The first corrosion-resistant and heat-resistant liquid of the present invention is composed of tin, zinc, titanium and carbon nanotubes dispersed by additives, wherein the carbon nanotubes form a skeleton, which improves the peeling strength of the coating of the first corrosion-resistant and heat-resistant liquid and avoids the occurrence of the "powder falling" phenomenon; the tin, zinc and titanium contained therein can form a dense and stable passivation film, which improves the corrosion resistance and heat resistance of the coating of the first corrosion-resistant and heat-resistant liquid. The second corrosion-resistant and heat-resistant liquid of the present invention includes chromium, nickel and cobalt. Compared with the existing technology that requires the addition of rare metals such as niobium and molybdenum, the present invention reduces costs. In addition, the present invention can make the tin in the first corrosion-resistant and heat-resistant liquid distributed on the surface of the coating of the first corrosion-resistant and heat-resistant liquid by controlling the process conditions of electroplating, thereby improving the roughness of the coating and improving the bonding strength between the coating of the first corrosion-resistant and heat-resistant liquid and the coating of the second corrosion-resistant and heat-resistant liquid, solving the contradiction between the high cost caused by adding rare metals and the easy shedding of the coating caused by not adding rare metals.

[0034] The present invention also provides the electrolytic copper foil prepared by the method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil.

[0035] The present invention also provides application of the electrolytic copper foil in printed circuit boards.

[0036] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0037] Example 1

[0038] Preparation of electrolytic copper foil for printed circuit boards:

[0039] (1) Roughening: Place the copper foil in the roughening solution for 10 seconds. Keep it in the roughening solution. 2+ The concentration of is 10g / L, the concentration of H2SO4 is 160g / L, and the concentration of Zn 2+ The concentration of 2g / L; the current density of the coarsening is maintained at 71A / dm 2 ;

[0040] (2) Curing: Place the roughened copper foil in the curing liquid for 20 seconds to obtain the pretreated copper foil; keep the copper foil in the curing liquid. 2+The concentration of H2SO4 is 25g / L and 90g / L; the current density for curing is 42A / dm 2 ;

[0041] (3) Corrosion and heat resistance treatment: The pretreated copper foil is first placed in the first corrosion and heat resistance liquid at 15A / dm 2 The first electroplating was carried out for 120s at a current density of 10A / dm 2 The second electroplating was carried out for 20s at a current density of , and then dried at 60 ° C for 30min to obtain an electrolytic copper foil; the first corrosion-resistant and heat-resistant solution was kept, Sn 2+ The concentration of Zn is 20g / L, 2+ The concentration of the second corrosion-resistant and heat-resistant liquid is 7g / L, the concentration of carbon nanotubes (diameter 20nm) is 4g / L, the concentration of titanium tetrachloride is 10g / L, the concentration of potassium pyrophosphate is 75g / L, and the concentration of polyethylene glycol is 20mg / L; in the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 95g / L, and the concentration of Cr 3+ The concentration is 10g / L, Ni 2+ The concentration is 7g / L, Co 2+ The concentration is 3g / L.

[0042] Example 2

[0043] Preparation of electrolytic copper foil for printed circuit boards:

[0044] (1) Roughening: Place the copper foil in the roughening solution for 8 seconds. Keep it in the roughening solution. 2+ The concentration of is 12g / L, the concentration of H2SO4 is 155g / L, and the concentration of Zn 2+ The concentration of 2g / L; the current density of the coarsening was maintained at 75A / dm 2 ;

[0045] (2) Curing: Place the roughened copper foil in the curing liquid for 25 seconds to obtain the pretreated copper foil; keep the copper foil in the curing liquid. 2+ The concentration of H2SO4 is 22g / L and 95g / L; the current density for curing is 40A / dm 2 ;

[0046] (3) Corrosion and heat resistance treatment: The pretreated copper foil is first placed in the first corrosion and heat resistance liquid at 18A / dm 2 The first electroplating was carried out for 75s at a current density of 15A / dm 2 The second electroplating was carried out for 22s at a current density of , and then dried at 60 ° C for 30min to obtain an electrolytic copper foil; the first corrosion-resistant and heat-resistant solution was kept, Sn 2+ The concentration of Zn is 25g / L,2+ The concentration of the second corrosion-resistant and heat-resistant liquid is 6 g / L, the concentration of carbon nanotubes (diameter 21 nm) is 4 g / L, the concentration of titanium tetrachloride is 13 g / L, the concentration of potassium pyrophosphate is 70 g / L, and the concentration of polyethylene glycol is 25 mg / L; in the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 100 g / L, and the concentration of Cr 3+ The concentration of Ni is 12g / L, 2+ The concentration is 5g / L, Co 2+ The concentration is 3g / L.

[0047] Example 3

[0048] Preparation of electrolytic copper foil for printed circuit boards:

[0049] (1) Roughening: Place the copper foil in the roughening solution for 7 seconds. Keep it in the roughening solution. 2+ The concentration of H2SO4 is 15g / L, the concentration of Zn is 170g / L, 2+ The concentration of 1g / L; the current density of the coarsening is maintained at 78A / dm 2 ;

[0050] (2) Curing: The roughened copper foil is placed in a curing solution for 24 seconds to obtain a pretreated copper foil; the copper foil is kept in the curing solution. 2+ The concentration of H2SO4 is 25g / L and 100g / L; the current density for curing is 46A / dm 2 ;

[0051] (3) Corrosion and heat resistance treatment: The pretreated copper foil is first placed in the first corrosion and heat resistance liquid at 19A / dm 2 The first electroplating was carried out for 110s at a current density of 12A / dm 2 The second electroplating was carried out for 28s at a current density of , and then dried at 70 ° C for 30min to obtain an electrolytic copper foil; the first corrosion-resistant and heat-resistant solution was kept, Sn 2+ The concentration of Zn is 30g / L, 2+ The concentration of the second corrosion-resistant and heat-resistant liquid is 8g / L, the concentration of carbon nanotubes (diameter 25nm) is 3.5g / L, the concentration of titanium tetrachloride is 15g / L, the concentration of potassium pyrophosphate is 75g / L, and the concentration of polyethylene glycol is 20mg / L; in the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 110g / L, and the concentration of Cr 3+ The concentration of Ni is 14g / L, 2+ The concentration is 7g / L, Co 2+ The concentration is 3.5g / L.

[0052] Example 4

[0053] Preparation of electrolytic copper foil for printed circuit boards:

[0054] (1) Roughening: Place the copper foil in the roughening solution for 10 seconds. Keep it in the roughening solution. 2+ The concentration of is 10g / L, the concentration of H2SO4 is 180g / L, and the concentration of Zn 2+ The concentration of 2g / L; the current density of the coarsening was maintained at 75A / dm 2 ;

[0055] (2) Curing: Place the roughened copper foil in the curing liquid for 30 seconds to obtain the pretreated copper foil; keep the copper foil in the curing liquid. 2+ The concentration of H2SO4 is 21g / L and 93g / L; the current density for curing is 42A / dm 2 ;

[0056] (3) Corrosion and heat resistance treatment: The pretreated copper foil is first placed in the first corrosion and heat resistance liquid at 20A / dm 2 The first electroplating was carried out for 80s at a current density of 14A / dm 2 The second electroplating was carried out for 25s at a current density of , and then dried at 70 ° C for 30min to obtain an electrolytic copper foil; the first corrosion-resistant and heat-resistant solution was kept, Sn 2+ The concentration of Zn is 25g / L, 2+ The concentration of the second corrosion-resistant and heat-resistant liquid is 10g / L, the concentration of carbon nanotubes (diameter 25nm) is 3.8g / L, the concentration of titanium tetrachloride is 12g / L, the concentration of potassium pyrophosphate is 75g / L, and the concentration of polyethylene glycol is 30mg / L; in the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 120g / L, and the concentration of Cr 3+ The concentration of Ni is 11g / L, 2+ The concentration is 6g / L, Co 2+ The concentration is 3g / L.

[0057] The corrosion resistance, heat resistance and peel strength of the electrolytic copper foils obtained in Examples 1 to 4 were tested. The test methods and results are as follows:

[0058] Test method: The corrosion resistance, heat resistance and peeling strength of the electrolytic copper foils obtained in Examples 1 to 4 were characterized by the peeling strength under high temperature, acidic and alkaline environments.

[0059] (1) Determine the peel strength of the electrolytic copper foils obtained in Examples 1 to 4 under a normal environment (temperature of 24° C., humidity of 52%), and record it as the peel strength under normal conditions;

[0060] (2) The electrolytic copper foils obtained in Examples 1 to 4 were placed in a drying oven at 380° C. for 90 minutes. The electrolytic copper foils after drying oven treatment were taken out and their peel strength was measured, which was recorded as the peel strength at 380° C.

[0061] (3) The electrolytic copper foils obtained in Examples 1 to 4 were placed in a thermostat, maintained at a temperature of 25° C. and a humidity of 99% for 5 hours. The electrolytic copper foils after the thermostat treatment were taken out and the peel strength was measured, which was recorded as the peel strength under 99% humidity conditions.

[0062] (4) The electrolytic copper foil obtained in Examples 1 to 4 was immersed in sulfuric acid with a mass concentration of 70%. After 25 minutes, the electrolytic copper foil soaked in sulfuric acid was taken out and the peel strength was measured, which was recorded as the peel strength under acidic conditions;

[0063] (5) The electrolytic copper foil obtained in Examples 1 to 4 was immersed in ammonia water with a mass concentration of 55%. After 30 minutes, the electrolytic copper foil soaked in ammonia water was taken out and the peeling strength was measured, which was recorded as the peeling strength under alkaline conditions. The measurement results are shown in Table 1.

[0064] Table 1 Performance test results of the electrolytic copper foil obtained in Examples 1 to 4

[0065]

[0066] As shown in Table 1, the electrolytic copper foil obtained by the present invention has high peel strength and can maintain high peel strength under high temperature, high humidity, alkaline and acidic conditions. This shows that the corrosion resistance and high temperature resistance of the electrolytic copper foil obtained by the present invention can reach a high level.

[0067] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil, characterized in that: The steps include: (1) Roughening and curing: The copper foil is placed in a roughening solution for roughening, and then the roughened copper foil is placed in a curing solution for curing to obtain a pretreated copper foil; (2) Corrosion and heat resistant treatment: the pretreated copper foil is first placed in a first corrosion and heat resistant solution for the first electroplating, and then placed in a second corrosion and heat resistant solution for the second electroplating to obtain an electrolytic copper foil; In the first corrosion-resistant and heat-resistant liquid, Sn 2+ The concentration of Zn is 20~30g / L, 2+ The concentration of is 5~10g / L, the concentration of carbon nanotubes is 3.1~4.2g / L, the concentration of titanium tetrachloride is 10~15g / L, the concentration of potassium pyrophosphate is 70~80g / L, and the concentration of additives is 20~30mg / L; The additive is polyethylene glycol and / or lauryl polyoxyethylene ether; The current density of the first electroplating is 15~20A / dm 2 The first electroplating time is 60~120s; In the second corrosion-resistant and heat-resistant liquid, the concentration of potassium pyrophosphate is 90-120 g / L, Cr 3+ The concentration of Ni is 10~15g / L, 2+ The concentration is 5~8g / L, Co 2+ The concentration is 3~5g / L.

2. The method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil according to claim 1, characterized in that: In the roughening solution, Cu 2+ The concentration of is 10~15g / L, the concentration of H2SO4 is 150~180g / L, and the concentration of Zn 2+ The concentration is 1~4g / L; the current density of the roughening is 70~80A / dm 2 ; The coarsening time is 6~10s.

3. The method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil according to claim 2, characterized in that: In the solidification liquid, Cu 2+ The concentration of H2SO4 is 20~25g / L, the concentration of H2SO4 is 90~100g / L; the curing current density is 40~50A / dm 2 ; The curing time is 20~30s.

4. The method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil according to claim 3, characterized in that: The current density of the second electroplating is 10~15A / dm 2 ; The time of the second electroplating is 20~30s.

5. The electrolytic copper foil prepared by the method for preparing the highly corrosion-resistant, heat-resistant and peeling-resistant electrolytic copper foil according to any one of claims 1 to 4.

6. Use of the electrolytic copper foil according to claim 5 in printed circuit boards.

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