Surface anti-oxidation treatment process of copper foil for chip substrate, special electrolyte and application of surface anti-oxidation treatment process

Abstract

The invention discloses a copper foil surface anti-oxidation treatment process for a chip substrate, which comprises the following steps: placing a copper foil as a cathode in an electrolyte, and carrying out electro-deposition under the action of a direct-current electric field; the electrolyte comprises zinc sulfate, nickel sulfate, sodium hydroxymethyl sulfonate, boric acid, sodium benzoate, benzotriazole and lauryl sodium sulfate; and after electro-deposition, drying at 200-250 DEG C to form a zinc-nickel alloy protective layer on the surface of the copper foil. The invention further discloses a copper foil adopting the anti-oxidation treatment process, the surface of the copper foil is covered with a zinc-nickel alloy protective layer, and the copper foil is free of oxidation and color change after being baked for 1 hour at the temperature of 250 DEG C. A metallurgical bonding protective layer is formed through zinc-nickel alloy electro-deposition, and the surface powder falling phenomenon caused by traditional chemical / mechanical coarsening is fundamentally avoided. And the alloy film and the copper foil substrate form atomic-scale combination, so that the adhesive force with other materials is remarkably enhanced. The single process synchronously realizes strengthening and anti-oxidation protection of the conductive layer, and replaces the traditional coarsening and anti-oxidation process of step-by-step treatment.

Description

Technical Field

[0001] The present invention relates to the technical field of metal material surface treatment, and in particular to a surface anti-oxidation treatment process for copper foil used for chip substrates, a special electrolyte and applications thereof. Background Art

[0002] With the development of electronic technology, chip substrates, as an important component of electronic components, have increasingly higher requirements for high-temperature performance and anti-oxidation performance. Using copper foil as the conductive layer of chip substrates can improve their high-temperature performance and anti-oxidation performance to a certain extent.

[0003] Copper foil for chip substrates must have good electrical conductivity, thermal stability, and mechanical strength in high-temperature environments. First, in high-temperature environments, copper foil for chip substrates should be able to maintain stable electrical conductivity to ensure the normal operation of electronic components. At the same time, copper foil for chip substrates also needs to have high thermal stability and not deform or oxidize at high temperatures, thereby reducing performance. Since copper foil for chip substrates usually needs to undergo multiple high-temperature welding or hot pressing processes, copper foil for chip substrates also needs to have excellent anti-oxidation properties to prevent oxidation reactions from occurring in high-temperature environments, thereby reducing electrical conductivity. Surface oxidation of copper foil will increase its resistance, thereby affecting the performance of electronic components. Therefore, copper foil for chip substrates needs to have high antioxidant capacity and be able to maintain good electrical conductivity for a long time in high-temperature environments.

[0004] The following problems exist with copper foil for traditional chip substrates:

[0005] 1. Insufficient high-temperature stability: During multiple welding or hot pressing processes, copper foil is prone to oxidation and deformation, resulting in decreased conductivity;

[0006] 2. Defects in anti-oxidation performance: Traditional chemical roughening or mechanical roughening processes are prone to causing surface powder loss, and the step-by-step roughening + anti-oxidation process is inefficient;

[0007] 3. Weak interface bonding: The difference in thermal expansion coefficient between copper foil and resin substrate can easily lead to warping, affecting device reliability;

[0008] 4. Narrow process window: The existing electrodeposition process is prone to produce dendrites and uneven texture, and the film uniformity is less than 90%.

[0009] Therefore, there is an urgent need to develop a copper foil processing process that can simultaneously improve high-temperature conductivity, oxidation resistance and interface bonding strength. Summary of the Invention

[0010] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a surface anti-oxidation treatment process for copper foil used for chip substrates, a special electrolyte, and a copper foil treated by the process with high temperature stability and anti-oxidation properties.

[0011] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0012] A process for anti-oxidation treatment of the surface of copper foil for a core substrate comprises the following steps:

[0013] The copper foil is placed in the electrolyte as the cathode and electrodeposition is carried out under the action of a DC electric field;

[0014] The electrolyte comprises zinc sulfate, nickel sulfate, sodium hydroxymethanesulfonate, boric acid, sodium benzoate, benzotriazole and sodium lauryl sulfate;

[0015] After electrodeposition, the copper foil is directly dried and rolled up to form a zinc-nickel alloy protective layer on the surface of the copper foil.

[0016] The concentration of each component in the electrolyte is:

[0017] Zinc sulfate 60-120g / L, nickel sulfate 40-80g / L, sodium hydroxymethanesulfonate 5-25g / L, boric acid 10-50g / L, sodium benzoate 50-80g / L, benzotriazole 0.5-5g / L, sodium lauryl sulfate 0.1-5g / L.

[0018] The electrodeposition is carried out under the following conditions: electrolyte temperature 20-50°C, flow rate 30-50m³ / H, constant current density, and the electrodeposition is carried out in a continuous production device, the copper foil is moved at a constant speed through a traction mechanism, and the electrolyte is circulated and replenished.

[0019] The thickness of the zinc-nickel alloy protective layer is 0.05-1 μm.

[0020] An electrolyte for use in an anti-oxidation treatment process for the surface of a copper foil used for a chip substrate comprises the following components:

[0021] Zinc sulfate, nickel sulfate, sodium hydroxymethane sulfonate, boric acid, sodium benzoate, benzotriazole, and sodium lauryl sulfate.

[0022] The electrolyte is prepared according to the following steps:

[0023] (a) Dissolve each component in deionized water to form an independent solution;

[0024] (b) Pour each solution into a thermostatic stirring tank and stir at 40-45°C for 60 minutes;

[0025] (c) Make up to the target volume with deionized water.

[0026] In step (a), zinc sulfate is dissolved in 6 kg / 20 L of water, nickel sulfate is dissolved in 4 kg / 20 L of water, sodium hydroxymethanesulfonate is dissolved in 0.5 kg / 5 L of water, boric acid is dissolved in 1 kg / 5 L of water, sodium benzoate is dissolved in 5 kg / 20 L of water, benzotriazole is dissolved in 0.05 kg / 5 L of water, and sodium lauryl sulfate is dissolved in 0.02 kg / 5 L of water.

[0027] A copper foil produced using an anti-oxidation treatment process for copper foil used in chip substrates. Its surface is covered with a zinc-nickel alloy protective layer with a thickness of 0.05-1 μm. Suitable for chip substrate manufacturing, it exhibits a surface resistance change rate of ≤5% under high-temperature conditions.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. The present invention's copper foil surface anti-oxidation treatment process improves the foil's high-temperature stability and mechanical strength. The coating exhibits excellent corrosion resistance, effectively preventing oxidation and corrosion of the substrate in humid, acidic, and alkaline environments. Furthermore, the coating exhibits excellent wear resistance, effectively improving the substrate's surface hardness and wear resistance. Furthermore, the organic zinc-nickel alloy protective layer exhibits excellent electrochemical properties, including excellent conductivity and electrochemical stability. After baking at a constant temperature of 200-250°C for one hour, the copper foil exhibits no oxidation or color difference.

[0030] 2. The organic zinc-nickel alloy protective layer also exhibits excellent electrochemical properties. The alloy coating has excellent electrical conductivity, meeting the conductivity requirements of electronic equipment and other fields. Furthermore, the organic zinc-nickel alloy protective layer exhibits excellent electrochemical stability, is not susceptible to electrochemical reactions, and protects the substrate from damage.

[0031] 3. The organic zinc-nickel alloy protective layer can replace the traditional chrome plating process, while providing good corrosion resistance, wear resistance and anti-oxidation effects, it also reduces pollution to the environment.

[0032] 4. The organic zinc-nickel alloy protective layer process has clear process flow and parameter control requirements. This coating has excellent performance and broad application prospects. In the future, with the continuous advancement of electronic technology and the expansion of its applications, the requirements for the high-temperature performance and oxidation resistance of copper foil used in chip substrates will be further improved. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0034] The present invention provides a technical solution: a process for anti-oxidation treatment of the surface of copper foil for a core substrate, comprising the following steps:

[0035] The copper foil is placed in the electrolyte as the cathode and electrodeposition is carried out under the action of a DC electric field;

[0036] The electrolyte contains zinc sulfate, nickel sulfate, sodium hydroxymethanesulfonate, boric acid, sodium benzoate, benzotriazole and sodium lauryl sulfate;

[0037] After electrodeposition, the copper foil is dried and rolled up at 200-250°C to form a zinc-nickel alloy protective layer on the surface of the copper foil.

[0038] The metallurgically bonded protective layer formed by zinc-nickel alloy electrodeposition fundamentally avoids the surface powder loss caused by traditional chemical / mechanical roughening. This improves interfacial bonding, creating an atomic-level bond between the alloy film and the copper foil substrate, significantly enhancing adhesion to other materials. This dual-function integration allows for simultaneous conductive layer strengthening and oxidation protection in a single process, replacing the traditional step-by-step roughening and oxidation protection process.

[0039] The concentrations of the components in the electrolyte are: zinc sulfate 60-120 g / L, nickel sulfate 40-80 g / L, sodium hydroxymethylsulfonate 5-25 g / L, boric acid 10-50 g / L, sodium benzoate 50-80 g / L, benzotriazole 0.5-5 g / L, and sodium lauryl sulfate 0.1-5 g / L.

[0040] Synergistic effect of components: zinc sulfate / nickel constitutes the alloy skeleton, providing basic strength and conductivity; sodium hydroxymethane sulfonate + boric acid forms a buffer system to maintain pH stability during the deposition process; sodium benzoate / benzotriazole forms a passivation film in situ at the alloy grain boundary (blocking corrosion channels); sodium dodecyl sulfate eliminates hydrogen embrittlement (improving the toughness of the coating).

[0041] Wide concentration window: The concentration range design of each component increases the process tolerance by more than 3 times compared with traditional processes.

[0042] Electrodeposition process parameters meet the following requirements: electrolyte temperature of 20-50°C, flow rate of 30-50 m³ / H, and constant current density. Low-temperature deposition at 20-50°C combined with forced convection at 30-50 m³ / H inhibits dendrite growth, resulting in a dense nanoscale grain structure and addressing uneven texture. Constant current density ensures compositional consistency across the film thickness, preventing edge effects.

[0043] Electrodeposition is performed in a continuous production facility, where the copper foil is moved at a constant speed by a traction mechanism, while the electrolyte is circulated and replenished. This traction-and-circulation design ensures that the deposition interface is always exposed to fresh electrolyte, eliminating the "boundary layer effect" of traditional static tanks and improving film uniformity to over 95%.

[0044] The zinc-nickel alloy protective layer has a thickness of 0.05-1μm. This protective layer provides stress buffering at the metal-resin interface, preventing warping caused by differences in thermal expansion coefficients.

[0045] An electrolyte for use in an anti-oxidation treatment process for the surface of a copper foil used for a chip substrate comprises the following components:

[0046] Zinc sulfate, nickel sulfate, sodium hydroxymethane sulfonate, boric acid, sodium benzoate, benzotriazole, and sodium lauryl sulfate.

[0047] The electrolyte is prepared according to the following steps:

[0048] (a) Dissolve each component in deionized water to form an independent solution;

[0049] (b) Pour each solution into a thermostatic stirring tank and stir at 40-45°C for 60 minutes;

[0050] (c) Make up to the target volume with deionized water.

[0051] In step (a), zinc sulfate is dissolved in 6 kg / 20 L of water, nickel sulfate is dissolved in 4 kg / 20 L of water, sodium hydroxymethanesulfonate is dissolved in 0.5 kg / 5 L of water, boric acid is dissolved in 1 kg / 5 L of water, sodium benzoate is dissolved in 5 kg / 20 L of water, benzotriazole is dissolved in 0.05 kg / 5 L of water, and sodium lauryl sulfate is dissolved in 0.02 kg / 5 L of water.

[0052] A copper foil produced using an anti-oxidation treatment process, coated with a zinc-nickel alloy protective layer, exhibits no oxidation or discoloration after baking at 250°C for one hour. Suitable for chip substrate manufacturing, it exhibits a surface resistance change rate of ≤5% at high temperatures. It exhibits high-temperature structural stability, with the nickel element in the zinc-nickel alloy film inhibiting copper diffusion. After baking at 250°C, there is no copper oxidation or discoloration, compared to traditional copper foil that oxidizes at 80°C. Particularly suitable for chip substrate manufacturing, it exhibits a surface resistance change rate of ≤5% at high temperatures. The conductive network is optimized, and the alloy film forms a low-resistance interface layer, resulting in a surface resistance change of ≤5%, addressing the issue of conductive failure at high temperatures.

[0053] In summary, the copper foil surface anti-oxidation treatment process of the present invention can improve the high-temperature stability and mechanical strength of the copper foil. The coating has good corrosion resistance and can effectively prevent oxidation and corrosion of the substrate in humid, acidic, and alkaline corrosive environments. Secondly, the coating has excellent wear resistance and can effectively improve the surface hardness and wear resistance of the substrate. In addition, the organic zinc-nickel alloy protective layer also has good electrochemical properties, good electrical conductivity and electrochemical stability. The copper foil surface is not oxidized and has no color difference after baking at a constant temperature of 200-250 degrees for 1 hour.

[0054] The organic zinc-nickel alloy protective layer also exhibits excellent electrochemical properties. The alloy coating exhibits excellent electrical conductivity, meeting the conductivity requirements of electronic equipment and other applications. Furthermore, the organic zinc-nickel alloy protective layer exhibits excellent electrochemical stability, making it less susceptible to electrochemical reactions and protecting the substrate from damage.

[0055] The organic zinc-nickel alloy protective layer can replace the traditional chrome plating process, providing good corrosion resistance, wear resistance, and anti-oxidation effects while reducing pollution to the environment.

[0056] The organic zinc-nickel alloy protective coating process has clear process flow and parameter control requirements. This coating has excellent performance and broad application prospects. In the future, with the continuous advancement of electronic technology and the expansion of its applications, the requirements for the high-temperature performance and oxidation resistance of copper foil used in chip substrates will be further improved.

Claims

1. A process for anti-oxidation treatment of the surface of copper foil for chip substrate, characterized in that: The following steps are involved: The copper foil is placed in the electrolyte as the cathode and electrodeposition is carried out under the action of a DC electric field; The electrolyte comprises zinc sulfate, nickel sulfate, sodium hydroxymethanesulfonate, boric acid, sodium benzoate, benzotriazole and sodium lauryl sulfate; After electrodeposition, the copper foil is directly dried and rolled up to form a zinc-nickel alloy protective layer on the surface of the copper foil.

2. The process for anti-oxidation treatment of the surface of the copper foil for the chip substrate according to claim 1, characterized in that: The concentration of each component in the electrolyte is: Zinc sulfate 60-120g / L, nickel sulfate 40-80g / L, sodium hydroxymethanesulfonate 5-25g / L, boric acid 10-50g / L, sodium benzoate 50-80g / L, benzotriazole 0.5-5g / L, sodium lauryl sulfate 0.1-5g / L.

3. The process for anti-oxidation treatment of the surface of the copper foil for the chip substrate according to claim 1, characterized in that: The electrodeposition is carried out under the following conditions: electrolyte temperature 20-50°C, flow rate 30-50m³ / H, constant current density, and the electrodeposition is carried out in a continuous production device, the copper foil is moved at a constant speed through a traction mechanism, and the electrolyte is circulated and replenished.

4. The process for anti-oxidation treatment of the surface of the copper foil for the chip substrate according to claim 1, characterized in that: The thickness of the zinc-nickel alloy protective layer is 0.05-1 μm.

5. An electrolyte for use in the process according to any one of claims 1 to 4, characterized in that: Includes the following components: Zinc sulfate, nickel sulfate, sodium hydroxymethane sulfonate, boric acid, sodium benzoate, benzotriazole, and sodium lauryl sulfate.

6. The electrolyte according to the process of claim 5, characterized in that The electrolyte is prepared according to the following steps: (a) Dissolve each component in deionized water to form an independent solution; (b) Pour each solution into a thermostatic stirring tank and stir at 40-45°C for 60 minutes; (c) Make up to the target volume with deionized water.

7. The electrolyte according to the process of claim 5, characterized in that In step (a): Dissolve zinc sulfate at 6 kg / 20 L of water, nickel sulfate at 4 kg / 20 L of water, sodium hydroxymethanesulfonate at 0.5 kg / 5 L of water, boric acid at 1 kg / 5 L of water, sodium benzoate at 5 kg / 20 L of water, benzotriazole at 0.05 kg / 5 L of water, and sodium lauryl sulfate at 0.02 kg / 5 L of water.

8. A copper foil prepared by the process according to any one of claims 1 to 4, characterized in that: The surface of the zinc-nickel alloy protective layer is covered with a zinc-nickel alloy protective layer, and the thickness of the zinc-nickel alloy protective layer is 0.05-1 μm.

9. The copper foil according to claim 8, wherein It is suitable for chip substrate manufacturing, and the surface resistance change rate is ≤5% under high temperature environment.