Surface treatment method for improving heat resistance of high-speed plate electrolytic copper foil

Abstract

The invention belongs to the technical field of electrolytic copper foil surface treatment, and particularly relates to a surface treatment method for improving the heat resistance of a high-speed plate electrolytic copper foil, which comprises the following steps of: (1) pretreating a raw foil; (2) roughening treatment; (3) curing treatment; (4) heat-resistant layer treatment; (5) treating an anti-rust layer; (6) anti-oxidation treatment; (7) treating with a silane coupling agent; and (8) drying. The quaternary alloy is formed through co-deposition, the heat-resistant barrier layer is formed on the surface of the copper foil, compared with a conventional nickel plating process, the nickel-iron-tungsten-molybdenum quaternary alloy is formed through co-deposition and eutectoid in a heat-resistant layer electroplating solution by adopting sodium citrate as a complexing agent, the compact barrier layer is formed on the surface of the copper foil, and the heat-resistant barrier layer is formed on the surface of the copper foil. The copper foil has higher heat resistance, oxidation resistance and corrosion resistance; and saccharin in the heat-resistant layer treating fluid is used as a nickel plating brightener and has a synergistic effect with 1, 4-butynediol, so that a plating layer achieves the effect of smooth fine grains, and the uniform coverage of the plating layer is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of surface treatment of electrolytic copper foil, and particularly relates to a surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards. Background Art

[0002] When high-speed high-frequency alternating current signals are transmitted on the circuits of printed circuit boards, the current distribution inside the copper foil is uneven, and the current is concentrated in the thin layer on the outer surface of the conductor. This phenomenon is called the skin effect. Research shows that the higher the frequency of the transmitted signal, the more obvious the skin effect. Due to the skin effect, high-frequency signals are concentrated on the outer surface of the copper foil, and the effective cross-sectional area for transmission becomes smaller, resulting in an increase in the resistance of the copper foil surface layer and an increase in signal transmission loss. At the same time, due to the increase in the surface resistance of the copper foil, the proportion of high-frequency signals transmitted in the copper foil dissipated in the form of heat increases. In order to reduce the adverse effects of the skin effect on signal transmission, it is required that the copper foil has a low surface roughness. However, when the roughness of the copper foil is reduced, the bonding strength (peel strength) between the copper foil and the substrate also decreases. When the manufactured circuit board is assembled and welded with components of the whole machine, due to the influence of high temperature, the resin is easily cracked to generate small molecule compounds. If it comes into contact with the bare copper surface, it will react to release moisture, and the high-temperature vaporization of the moisture causes bubbling, which will separate the copper foil from the substrate. Therefore, how to produce electrolytic copper foil with low surface roughness and high heat resistance at the same time is an important technical problem to be solved by the present invention. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a surface treatment method for improving the heat resistance of electrolytic copper foil.

[0004] In order to achieve the above purpose, the technical solution adopted is as follows:

[0005] The purpose of the present invention is to provide a surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards, including the following steps:

[0006] (1) Raw foil pretreatment: Take the copper foil for high-speed boards and pickle it with a sulfuric acid solution with a mass fraction of 10 - 15%;

[0007] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution at a temperature of 25 - 30 °C and a current density of 8 - 10 A / dm 2 , and the electroplating time is 10 - 12 s;

[0008] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution at a temperature of 43 - 45 °C and a current density of 6 - 8 A / dm 2 , and the electroplating time is 6 - 8 s;

[0009] (4) Heat-resistant layer treatment: After the cured copper foil is washed with water, electroplating is carried out in the heat-resistant layer electroplating solution at a temperature of 40 - 70 °C and a current density of 0.8 - 7 A / dm 2 , the electroplating time is 4 - 17 s, the concentration of sodium citrate in the heat-resistant layer electroplating solution is 90 - 160 g / L, the concentration of ammonium sulfate is 10 - 30 g / L, the concentration of nickel sulfate is 6 - 20 g / L, the concentration of ferrous sulfate is 3 - 15 g / L, the concentration of sodium molybdate is 0.5 - 6 g / L, the concentration of sodium tungstate is 0.5 - 5 g / L, the concentration of 1,4 - butynediol is 0.1 - 1 g / L, and the concentration of saccharin is 1 - 5 g / L;

[0010] (5) Antirust layer treatment: After the copper foil treated with the heat-resistant layer is washed with water, electroplating is carried out in the antirust layer treatment solution at a temperature of 38 - 42 °C and a current density of 4 - 6 A / dm 2 , the electroplating time is 6 - 8 s;

[0011] (6) Antioxidation treatment: The copper foil treated with the antirust layer is subjected to antioxidant electroplating treatment in the antioxidant treatment solution at a temperature of 20 - 30 °C and a current density of 4 - 6 A / dm 2 , the electroplating time is 3 - 5 s;

[0012] (7) Silane coupling agent treatment: After the copper foil treated with antioxidant is washed with water, an aqueous solution of 3 - aminopropyltriethoxysilane with a mass concentration of 0.2 - 0.5% is sprayed;

[0013] (8) Drying: The copper foil treated with the silane coupling agent is dried at a temperature of 220 - 260 °C for a drying time of 4 - 6 s to obtain the finished foil.

[0014] Furthermore, in the heat-resistant layer electroplating solution described in step (4), the concentration of sodium citrate is 100 - 150 g / L, the concentration of ammonium sulfate is 15 - 25 g / L, the concentration of nickel sulfate is 8 - 15 g / L, the concentration of ferrous sulfate is 5 - 13 g / L, the concentration of sodium molybdate is 1 - 5 g / L, the concentration of sodium tungstate is 1.5 - 4 g / L, the concentration of 1,4 - butynediol is 0.2 - 0.8 g / L, the concentration of saccharin is 1.5 - 3.5 g / L, the temperature is 45 - 65 °C, the current density is 1.2 - 6.5 A / dm 2 , the electroplating time is 6 - 15 s.

[0015] Further, in the electroplating solution for the heat-resistant layer in step (4), the concentration of sodium citrate is 110-140 g / L, the concentration of ammonium sulfate is 17-23 g / L, the concentration of nickel sulfate is 10-14 g / L, the concentration of ferrous sulfate is 7-11 g / L, the concentration of sodium molybdate is 1.5-4.5 g / L, the concentration of sodium tungstate is 2-3.5 g / L, the concentration of 1,4-butyne diol is 0.4-0.6 g / L, the concentration of saccharin is 1.8-3.2 g / L, the temperature is 48-62 °C, and the current density is 2-6 A / dm 2 , and the electroplating time is 8-13 s.

[0016] Still further, in the electroplating solution for the heat-resistant layer in step (4), the concentration of sodium citrate is 120-130 g / L, the concentration of ammonium sulfate is 18-21 g / L, the concentration of nickel sulfate is 11-13 g / L, the concentration of ferrous sulfate is 8-10 g / L, the concentration of sodium molybdate is 2-4 g / L, the concentration of sodium tungstate is 2.5-3 g / L, the concentration of 1,4-butyne diol is 0.45-0.5 g / L, the concentration of saccharin is 2.2-2.8 g / L, the temperature is 52-58 °C, and the current density is 3-5 A / dm 2 , and the electroplating time is 9-12 s.

[0017] Further, in the roughening solution in step (2), the concentration of divalent copper ions is 12-25 g / L, and the concentration of sulfuric acid is 120-200 g / L.

[0018] Further, in the curing solution in step (3), the concentration of divalent copper ions is 60-80 g / L, and the concentration of sulfuric acid is 85-100 g / L.

[0019] Still further, in the antirust layer treatment solution in step (5), the concentration of potassium pyrophosphate is 120-150 g / L, the concentration of zinc ions is 6-8 g / L, the concentration of nickel ions is 1.5-3 g / L, and the concentration of molybdenum ions is 0.8-1.2 g / L.

[0020] Further, in the anti-oxidation treatment solution in step (6), the concentration of hexavalent chromium ions is 1.2-2.5 g / L, and the pH value is 10-12.

[0021] Compared with the prior art, the beneficial effects of the present invention are:

[0022] The present invention utilizes co - deposition to form a quaternary alloy and form a heat - resistant barrier layer on the surface of a copper foil. Compared with the conventional nickel - plating process, due to the presence of iron, molybdenum, and tungsten in the alloy coating of the present invention, the heat - resistant barrier layer structure on the copper foil surface can be made more dense and have higher heat resistance. The electroplating solution for the heat - resistant layer of the present invention uses sodium citrate as a complexing agent and co - deposits to eutectically form a nickel - iron - tungsten - molybdenum quaternary alloy. Molybdenum in the quaternary alloy has the characteristics of high specific heat and low coefficient of thermal expansion, which can make the heat resistance of the coating much higher than that of other conventional metal coatings. In addition, the addition of molybdenum can also make the coating have high chemical stability and be resistant to oxidation and corrosion. Tungsten is the metal with the highest melting point in nature, and iron can significantly improve the mechanical properties of the coating. The quaternary alloy formed by the eutectic of molybdenum, tungsten, iron and nickel forms a dense barrier layer on the copper foil surface, making the copper foil have higher heat resistance, oxidation resistance and corrosion resistance. Saccharin in the heat - resistant layer treatment solution, as a nickel - plating brightener, acts synergistically with 1,4 - butynediol to make the coating achieve a smooth and fine - grained effect and increase the uniform coverage of the coating. Sulfuric acid, as a conductive salt, can not only ensure uniform electroplating but also increase the hardness of the coating. In addition, the preparation method of the present invention is simple, environmentally friendly and has low cost. Detailed implementation mode

[0023] The principles and features of the present invention are described below in conjunction with examples. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0024] Example 1

[0025] A surface treatment method for improving the heat resistance of electrolytic copper foil for high - speed boards includes the following steps:

[0026] (1) Raw foil pretreatment: Take an 18μm electrolytic copper foil for high - speed boards and pickle it with a sulfuric acid solution with a mass fraction of 10%.

[0027] (2) Roughening treatment: Electroplate the pickled copper foil in a roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 12 g / L, the sulfuric acid concentration is 120 g / L, the temperature is 25 °C, the current density is 8 A / dm 2 , and the electroplating time is 12 s.

[0028] (3) Curing treatment: Electroplate the roughened copper foil in a curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 60 g / L, the concentration of sulfuric acid is 85 g / L, the temperature is 43 °C, the current density is 6 A / dm 2 , and the electroplating time is 8 s.

[0029] (4) Heat-resistant layer treatment: After the cured copper foil is washed with water, electroplating is carried out in the electroplating solution for the heat-resistant layer. The composition of the plating solution is: the concentration of sodium citrate is 125 g / L, the concentration of ammonium sulfate is 20 g / L, the concentration of nickel sulfate is 12 g / L, the concentration of ferrous sulfate is 9 g / L, the concentration of sodium molybdate is 3 g / L, the concentration of sodium tungstate is 2.8 g / L, the concentration of 1,4-butyne diol is 0.48 g / L, the concentration of saccharin is 2.5 g / L, the temperature is 55 °C, and the current density is 4 A / dm 2 , and the electroplating time is 10 s.

[0030] (5) Antirust layer treatment: After the copper foil treated with the heat-resistant layer is washed with water, electroplating is carried out in the antirust layer treatment solution. The composition of the plating solution is: the concentration of potassium pyrophosphate is 120 g / L, the concentration of zinc ions is 6 g / L, the concentration of nickel ions is 1.5 g / L, the concentration of molybdenum ions is 0.8 g / L, the temperature is 38 °C, and the current density is 4 A / dm 2 , and the electroplating time is 8 s.

[0031] (6) Antioxidation treatment: The copper foil treated with the antirust layer is subjected to antioxidation treatment. The composition of the antioxidation treatment solution is: the concentration of hexavalent chromium ions is 1.2 g / L, the pH value is 10, the temperature is 20 °C, and the current density is 4 A / dm 2 , and the electroplating time is 5 s.

[0032] (7) Silane coupling agent treatment: After the copper foil treated with antioxidation is washed with water, an aqueous solution of 3-aminopropyltriethoxysilane with a mass concentration of 0.2% is sprayed.

[0033] (8) Drying: The copper foil treated with the silane coupling agent is dried at a temperature of 220 °C for 5 s to obtain the finished foil.

[0034] Example 2

[0035] A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards includes the following steps:

[0036] (1) Raw foil pretreatment: Take an 18-μm electrolytic copper foil for high-speed boards and pickle it with a sulfuric acid solution with a mass fraction of 10%.

[0037] (2) Roughening treatment: The pickled copper foil is electroplated in the roughening solution. The composition of the roughening solution is: the concentration of divalent copper ions is 19 g / L, the concentration of sulfuric acid is 110 g / L, the temperature is 27 °C, and the current density is 9 A / dm 2 , and the electroplating time is 11 s.

[0038] (3) Curing treatment: The roughened copper foil is electroplated in the curing solution. The composition of the curing solution is: the concentration of divalent copper ions is 70 g / L, the concentration of sulfuric acid is 94 g / L, the temperature is 44 °C, and the current density is 7 A / dm2 , electroplating time: 7S.

[0039] (4) Heat-resistant layer treatment: After the cured copper foil is washed with water, electroplating is carried out in the electroplating solution for the heat-resistant layer. The composition of the plating solution is: sodium citrate concentration is 90g / L, ammonium sulfate concentration is 10g / L, nickel sulfate concentration is 6g / L, ferrous sulfate concentration is 3g / L, sodium molybdate concentration is 0.5g / L, sodium tungstate concentration is 0.5g / L, 1,4-butyne diol concentration is 0.1g / L, saccharin concentration is 1g / L, temperature is 40°C, and current density is 0.8A / dm 2 , electroplating time: 17S.

[0040] (5) Antirust layer treatment: After the copper foil treated with the heat-resistant layer is washed with water, electroplating is carried out in the antirust layer treatment solution. The composition of the plating solution is: potassium pyrophosphate concentration is 135g / L, zinc ion concentration is 7g / L, nickel ion concentration is 2.2g / L, molybdenum ion concentration is 1g / L, temperature is 40°C, and current density is 5A / dm 2 , electroplating time: 7S.

[0041] (6) Antioxidation treatment: The copper foil treated with the antirust layer is subjected to antioxidation treatment. The composition of the antioxidation treatment solution is: hexavalent chromium ion concentration is 1.5g / L, pH value is 11, temperature is 25°C, and current density is 5A / dm 2 , electroplating time: 4S.

[0042] (7) Silane coupling agent treatment: After the copper foil treated with antioxidation is washed with water, an aqueous solution of 3-aminopropyltriethoxysilane with a mass concentration of 0.4% is sprayed.

[0043] (8) Drying: The copper foil treated with the silane coupling agent is dried at a temperature of 240°C for 4S to obtain the finished foil.

[0044] Example 3

[0045] A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards includes the following steps:

[0046] (1) Raw foil pretreatment: Take an 18μm electrolytic copper foil for high-speed boards and pickle it with a sulfuric acid solution with a mass fraction of 15%.

[0047] (2) Roughening treatment: The pickled copper foil is electroplated in the roughening solution. The composition of the roughening solution is: divalent copper ion concentration is 25g / L, sulfuric acid concentration is 200g / L, temperature is 30°C, and current density is 10A / dm 2 , electroplating time: 10S.

[0048] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 80 g / L, the concentration of sulfuric acid is 100 g / L, the temperature is 45 °C, and the current density is 8 A / dm 2 , and the electroplating time is 6 s.

[0049] (4) Heat-resistant layer treatment: After washing the cured copper foil with water, electroplate it in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 160 g / L, the concentration of ammonium sulfate is 30 g / L, the concentration of nickel sulfate is 20 g / L, the concentration of ferrous sulfate is 15 g / L, the concentration of sodium molybdate is 6 g / L, the concentration of sodium tungstate is 5 g / L, the concentration of 1,4-butynediol is 1 g / L, the concentration of saccharin is 5 g / L, the temperature is 70 °C, and the current density is 7 A / dm 2 , and the electroplating time is 4 s.

[0050] (5) Antirust layer treatment: After washing the copper foil treated with the heat-resistant layer with water, electroplate it in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 150 g / L, the concentration of zinc ions is 8 g / L, the concentration of nickel ions is 3 g / L, the concentration of molybdenum ions is 1.2 g / L, the temperature is 42 °C, and the current density is 6 A / dm 2 , and the electroplating time is 6 s.

[0051] (6) Antioxidation treatment: Perform antioxidation treatment on the copper foil treated with the antirust layer. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 2.5 g / L, the pH value is 12, the temperature is 30 °C, and the current density is 6 A / dm 2 , and the electroplating time is 3 s.

[0052] (7) Silane coupling agent treatment: After washing the copper foil treated with antioxidation with water, spray a 0.5% aqueous solution of 3-aminopropyltriethoxysilane.

[0053] (8) Drying: Dry the copper foil treated with the silane coupling agent at a temperature of 260 °C for 4 s to obtain the finished foil.

[0054] Example 4

[0055] A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards includes the following steps:

[0056] (1) Raw foil pretreatment: Take the 18-μm electrolytic copper foil for high-speed boards and pickle it with a 12% sulfuric acid solution by mass fraction;

[0057] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 21 g / L, the sulfuric acid concentration is 150 g / L, the temperature is 28 °C, and the current density is 9 A / dm 2, electroplating time is 11S.

[0058] (3) Curing treatment: The roughened copper foil is electroplated in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 65g / L, the concentration of sulfuric acid is 90g / L, the temperature is 44°C, and the current density is 8A / dm 2 , electroplating time is 7S.

[0059] (4) Heat-resistant layer treatment: After the cured copper foil is washed with water, it is electroplated in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 140g / L, the concentration of ammonium sulfate is 25g / L, the concentration of nickel sulfate is 15g / L, the concentration of ferrous sulfate is 13g / L, the concentration of sodium molybdate is 5g / L, the concentration of sodium tungstate is 1.5g / L, the concentration of 1,4-butyne diol is 0.4g / L, the concentration of saccharin is 1.8g / L, the temperature is 50°C, and the current density is 6A / dm 2 , electroplating time is 8S.

[0060] (5) Antirust layer treatment: After the copper foil treated with the heat-resistant layer is washed with water, it is electroplated in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 130g / L, the concentration of zinc ions is 6g / L, the concentration of nickel ions is 1.8g / L, the concentration of molybdenum ions is 1.1g / L, the temperature is 39°C, and the current density is 5A / dm 2 , electroplating time is 7S.

[0061] (6) Antioxidation treatment: The copper foil treated with the antirust layer is subjected to antioxidation treatment. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 1.4g / L, the pH value is 11, the temperature is 28°C, and the current density is 6A / dm 2 , electroplating time is 4S.

[0062] (7) Silane coupling agent treatment: After the copper foil treated with antioxidation is washed with water, an aqueous solution of 3-aminopropyltriethoxysilane with a mass concentration of 0.3% is sprayed.

[0063] (8) Drying: The copper foil treated with the silane coupling agent is dried. The temperature is 225°C and the drying time is 6S, thus obtaining the finished foil.

[0064] Example 5

[0065] A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards includes the following steps:

[0066] (1) Raw foil pretreatment: Take an 18μm electrolytic copper foil for high-speed boards and pickle it with a sulfuric acid solution with a mass fraction of 10%.

[0067] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 13 g / L, the sulfuric acid concentration is 124 g / L, the temperature is 26 °C, and the current density is 10 A / dm 2 , and the electroplating time is 10 s.

[0068] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 78 g / L, the sulfuric acid concentration is 95 g / L, the temperature is 44 °C, and the current density is 8 A / dm 2 , and the electroplating time is 6 s.

[0069] (4) Heat-resistant layer treatment: After washing the cured copper foil with water, electroplate it in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 130 g / L, the concentration of ammonium sulfate is 21 g / L, the concentration of nickel sulfate is 18 g / L, the concentration of ferrous sulfate is 5 g / L, the concentration of sodium molybdate is 1 g / L, the concentration of sodium tungstate is 3 g / L, the concentration of 1,4-butyne diol is 0.8 g / L, the concentration of saccharin is 3.5 g / L, the temperature is 60 °C, and the current density is 2 A / dm 2 , and the electroplating time is 15 s.

[0070] (5) Antirust layer treatment: After washing the copper foil treated with the heat-resistant layer with water, electroplate it in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 138 g / L, the concentration of zinc ions is 7 g / L, the concentration of nickel ions is 2.8 g / L, the concentration of molybdenum ions is 1.1 g / L, the temperature is 41 °C, and the current density is 5 A / dm 2 , and the electroplating time is 6 s.

[0071] (6) Antioxidation treatment: Perform antioxidation treatment on the copper foil treated with the antirust layer. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 2.2 g / L, the pH value is 11, the temperature is 22 °C, and the current density is 5 A / dm 2 , and the electroplating time is 4 s.

[0072] (7) Silane coupling agent treatment: After washing the copper foil treated with antioxidation with water, spray a 0.3% aqueous solution of 3-aminopropyltriethoxysilane.

[0073] (8) Drying: Dry the copper foil treated with the silane coupling agent. The temperature is 250 °C, and the drying time is 5 s, then the finished foil is obtained.

[0074] Comparative Example 1

[0075] A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards includes the following steps:

[0076] (1) Pretreatment of raw foil: Take 18μm electrolytic copper foil for high-speed board, and pickle it with sulfuric acid solution with a mass fraction of 10%.

[0077] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 12g / L, the sulfuric acid concentration is 120g / L, the temperature is 25°C, the current density is 8A / dm 2 , and the electroplating time is 12S.

[0078] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 60g / L, the sulfuric acid concentration is 85g / L, the temperature is 43°C, the current density is 6A / dm 2 , and the electroplating time is 8S.

[0079] (4) Heat-resistant layer treatment: After washing the cured copper foil with water, electroplate it in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 125g / L, the concentration of ammonium sulfate is 20g / L, the concentration of nickel sulfate is 12g / L, the concentration of sodium molybdate is 3g / L, the concentration of sodium tungstate is 2.8g / L, the concentration of 1,4-butynediol is 0.48g / L, the concentration of saccharin is 2.5g / L, the temperature is 55°C, and the current density is 4A / dm 2 , and the electroplating time is 10S.

[0080] (5) Antirust layer treatment: After washing the copper foil treated with the heat-resistant layer with water, electroplate it in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 120g / L, the concentration of zinc ions is 6g / L, the concentration of nickel ions is 1.5g / L, the concentration of molybdenum ions is 0.8g / L, the temperature is 38°C, and the current density is 4A / dm 2 , and the electroplating time is 8S.

[0081] (6) Antioxidation treatment: Perform antioxidation treatment on the copper foil treated with the antirust layer. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 1.2g / L, the pH value is 10, the temperature is 20°C, and the current density is 4A / dm 2 , and the electroplating time is 5S.

[0082] (7) Silane coupling agent treatment: After washing the copper foil treated with antioxidation with water, spray an aqueous solution of 3-aminopropyltriethoxysilane with a mass concentration of 0.2%.

[0083] (8) Drying: Dry the copper foil treated with the silane coupling agent at a temperature of 220°C for 5S to obtain the finished foil.

[0084] Comparative Example 2

[0085] A surface treatment method for improving the heat resistance of high-speed board electrolytic copper foil includes the following steps:

[0086] (1) Raw foil pretreatment: Take the 18μm electrolytic copper foil for high-speed board and pickle it with a sulfuric acid solution with a mass fraction of 10%.

[0087] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 12g / L, the sulfuric acid concentration is 120g / L, the temperature is 25°C, and the current density is 8A / dm 2 , and the electroplating time is 12S.

[0088] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 60g / L, the sulfuric acid concentration is 85g / L, the temperature is 43°C, and the current density is 6A / dm 2 , and the electroplating time is 8S.

[0089] (4) Heat-resistant layer treatment: After washing the cured copper foil with water, electroplate it in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 125g / L, the concentration of ammonium sulfate is 20g / L, the concentration of nickel sulfate is 12g / L, the concentration of ferrous sulfate is 9g / L, the concentration of sodium tungstate is 2.8g / L, the concentration of 1,4-butynediol is 0.48g / L, the concentration of saccharin is 2.5g / L, the temperature is 55°C, and the current density is 4A / dm 2 , and the electroplating time is 10S.

[0090] (5) Antirust layer treatment: After washing the copper foil treated with the heat-resistant layer with water, electroplate it in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 120g / L, the concentration of zinc ions is 6g / L, the concentration of nickel ions is 1.5g / L, the concentration of molybdenum ions is 0.8g / L, the temperature is 38°C, and the current density is 4A / dm 2 , and the electroplating time is 8S.

[0091] (6) Antioxidation treatment: Perform antioxidation treatment on the copper foil treated with the antirust layer. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 1.2g / L, the pH value is 10, the temperature is 20°C, and the current density is 4A / dm 2 , and the electroplating time is 5S.

[0092] (7) Silane coupling agent treatment: After washing the copper foil treated with antioxidation with water, spray a 0.2% aqueous solution of 3-aminopropyltriethoxysilane.

[0093] (8) Drying: Dry the copper foil treated with the silane coupling agent at a temperature of 220°C for 5S to obtain the finished foil.

[0094] Comparative Example 3

[0095] A surface treatment method for improving the heat resistance of high-speed board electrolytic copper foil includes the following steps:

[0096] (1) Raw foil pretreatment: Take 18μm electrolytic copper foil for high-speed board and pickle it with a sulfuric acid solution with a mass fraction of 10%.

[0097] (2) Roughening treatment: Electroplate the pickled copper foil in the roughening solution. The composition of the roughening solution is that the concentration of divalent copper ions is 12g / L, the sulfuric acid concentration is 120g / L, the temperature is 25°C, and the current density is 8A / dm 2 , and the electroplating time is 12S.

[0098] (3) Curing treatment: Electroplate the roughened copper foil in the curing solution. The composition of the curing solution is that the concentration of divalent copper ions is 60g / L, the concentration of sulfuric acid is 85g / L, the temperature is 43°C, and the current density is 6A / dm 2 , and the electroplating time is 8S.

[0099] (4) Heat-resistant layer treatment: After washing the cured copper foil with water, electroplate it in the heat-resistant layer electroplating solution. The composition of the plating solution is that the concentration of sodium citrate is 125g / L, the concentration of ammonium sulfate is 20g / L, the concentration of nickel sulfate is 12g / L, the concentration of ferrous sulfate is 9g / L, the concentration of sodium molybdate is 3g / L, the concentration of 1,4-butyne diol is 0.48g / L, the concentration of saccharin is 2.5g / L, the temperature is 55°C, and the current density is 4A / dm 2 , and the electroplating time is 10S.

[0100] (5) Antirust layer treatment: After washing the copper foil treated with the heat-resistant layer with water, electroplate it in the antirust layer treatment solution. The composition of the plating solution is that the concentration of potassium pyrophosphate is 120g / L, the concentration of zinc ions is 6g / L, the concentration of nickel ions is 1.5g / L, the concentration of molybdenum ions is 0.8g / L, the temperature is 38°C, and the current density is 4A / dm 2 , and the electroplating time is 8S.

[0101] (6) Antioxidation treatment: Perform antioxidation treatment on the copper foil treated with the antirust layer. The composition of the antioxidation treatment solution is that the concentration of hexavalent chromium ions is 1.2g / L, the pH value is 10, the temperature is 20°C, and the current density is 4A / dm 2 , and the electroplating time is 5S.

[0102] (7) Silane coupling agent treatment: After washing the copper foil treated with antioxidation with water, spray a 0.2% aqueous solution of 3-aminopropyltriethoxysilane.

[0103] (8) Drying: The copper foil treated with the silane coupling agent is dried at a temperature of 220 °C for 5 s to obtain the finished foil.

[0104] Testing

[0105] The electrolytic copper foils obtained in Examples 1-5 and Comparative Examples 1-3 were used to press high-speed substrates with ULL-level polyphenylene ether system resins, and initial and high-temperature peel strength tests were carried out. The test results are shown in Table 1. Among them, the high-temperature peel strength was measured after dipping in molten tin at 288 °C, and the attenuation rate = (initial peel strength - peel strength after dipping in molten tin) ÷ initial peel strength × 100%.

[0106] Table 1. Performance test of electrolytic copper foils in Examples 1-5 and Comparative Examples 1-3

[0107]

[0108] As can be seen from Table 1, the peel strengths of Examples 1-5 after dipping in molten tin at 288 °C for 3 min and 5 min were very close to the initial values, without obvious attenuation, and the attenuation rates after dipping in molten tin for 10 min were all within 5%, with very little attenuation; compared with Example 1, ferrous sulfate, sodium molybdate, and sodium tungstate were respectively missing in Comparative Example 1, Comparative Example 2, and Comparative Example 3. The peel strength of the obtained electrolytic copper foil and the attenuation rate of the peel strength after dipping in molten tin for 3 min were both above 10%, the attenuation rate of the peel strength after dipping in molten tin for 5 min was both above 20%, and the attenuation rate of the peel strength after dipping in molten tin for 10 min was as high as nearly 40%, indicating that the nickel-iron-tungsten-molybdenum quaternary alloy heat-resistant barrier layer formed on the copper foil surface of the present invention greatly improves the heat resistance of the copper foil.

[0109] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards, characterized in that: The steps include: (1) Pretreatment of raw foil: Take the raw copper foil for high-speed board and pickle it with a sulfuric acid solution with a mass fraction of 10-15%; (2) Roughening treatment: The pickled copper foil is electroplated in a roughening solution at a temperature of 25-30°C and a current density of 8-10A / dm 2 , electroplating time 10-12S; (3) Curing treatment: The roughened copper foil is electroplated in the curing solution at a temperature of 43-45°C and a current density of 6-8A / dm 2 , electroplating time 6-8S; (4) Heat-resistant layer treatment: After the cured copper foil is washed with water, it is electroplated in a heat-resistant layer plating solution at a temperature of 40-70°C and a current density of 0.8-7A / dm 2 , electroplating time 4-17S, the concentration of sodium citrate in the heat-resistant layer plating solution is 90-160g / L, the concentration of ammonium sulfate is 10-30g / L, the concentration of nickel sulfate is 6-20g / L, the concentration of ferrous sulfate is 3-15g / L, the concentration of sodium molybdate is 0.5-6g / L, the concentration of sodium tungstate is 0.5-5g / L, the concentration of 1,4-butynediol is 0.1-1g / L, and the concentration of saccharin is 1-5g / L; (5) Anti-rust layer treatment: After the copper foil treated with the heat-resistant layer is washed with water, it is electroplated in the anti-rust layer treatment solution at a temperature of 38-42°C and a current density of 4-6A / dm 2 , electroplating time 6-8S; (6) Anti-oxidation treatment: The copper foil after anti-rust layer treatment is subjected to anti-oxidation electroplating treatment in an anti-oxidation treatment solution at a temperature of 20-30°C and a current density of 4-6A / dm 2 , electroplating time is 3-5S; (7) Silane coupling agent treatment: After the anti-oxidation treatment, the copper foil is washed with water and then sprayed with a 0.2-0.5% mass concentration of 3-aminopropyltriethoxysilane aqueous solution; (8) Drying: The copper foil treated with the silane coupling agent is dried at a temperature of 220-260° C. for 4-6 seconds to obtain a finished foil.

2. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 1, characterized in that: In the heat-resistant layer plating solution of step (4), the concentration of sodium citrate is 100-150 g / L, the concentration of ammonium sulfate is 15-25 g / L, the concentration of nickel sulfate is 8-15 g / L, the concentration of ferrous sulfate is 5-13 g / L, the concentration of sodium molybdate is 1-5 g / L, the concentration of sodium tungstate is 1.5-4 g / L, the concentration of 1,4-butynediol is 0.2-0.8 g / L, the concentration of saccharin is 1.5-3.5 g / L, the temperature is 45-65 ° C, and the current density is 1.2-6.5 A / dm 2 , the electroplating time is 6-15S.

3. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 2, characterized in that: In the heat-resistant layer plating solution of step (4), the concentration of sodium citrate is 110-140 g / L, the concentration of ammonium sulfate is 17-23 g / L, the concentration of nickel sulfate is 10-14 g / L, the concentration of ferrous sulfate is 7-11 g / L, the concentration of sodium molybdate is 1.5-4.5 g / L, the concentration of sodium tungstate is 2-3.5 g / L, the concentration of 1,4-butynediol is 0.4-0.6 g / L, the concentration of saccharin is 1.8-3.2 g / L, the temperature is 48-62 ° C, and the current density is 2-6 A / dm 2 , the electroplating time is 8-13S.

4. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 1, characterized in that: In the heat-resistant layer plating solution of step (4), the concentration of sodium citrate is 120-130 g / L, the concentration of ammonium sulfate is 18-21 g / L, the concentration of nickel sulfate is 11-13 g / L, the concentration of ferrous sulfate is 8-10 g / L, the concentration of sodium molybdate is 2-4 g / L, the concentration of sodium tungstate is 2.5-3 g / L, the concentration of 1,4-butynediol is 0.45-0.5 g / L, the concentration of saccharin is 2.2-2.8 g / L, the temperature is 52-58 ° C, and the current density is 3-5 A / dm 2 , the electroplating time is 9-12S.

5. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 1, characterized in that: In step (2), the concentration of divalent copper ions in the roughening solution is 12-25 g / L, and the concentration of sulfuric acid is 120-200 g / L.

6. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 1, characterized in that: In step (3), the concentration of divalent copper ions in the curing solution is 60-80 g / L, and the concentration of sulfuric acid is 85-100 g / L.

7. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 1, characterized in that: In step (5), the potassium pyrophosphate concentration in the anti-rust layer treatment liquid is 120-150 g / L, the zinc ion concentration is 6-8 g / L, the nickel ion concentration is 1.5-3 g / L, and the molybdenum ion concentration is 0.8-1.2 g / L.

8. The surface treatment method for improving the heat resistance of electrolytic copper foil for high-speed boards according to claim 7, characterized in that: In the anti-oxidation treatment solution of step (6), the concentration of hexavalent chromium ions is 1.2-2.5 g / L, and the pH value is 10-12.

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