Copper deposition composition and chemical copper deposition process

Abstract

The invention relates to the technical field of copper deposition compositions, in particular to a copper deposition composition and a chemical copper deposition process, and the copper deposition composition at least comprises a copper ion source, a complexing agent, a stabilizing agent, a reducing agent, an alkaline regulator and a solvent; wherein the stabilizing agent is selected from at least one of 2-2 bipyridine, potassium selenide, potassium thiocyanate or 2-mercapto benzimidazole, the problems that a copper deposition tank in the market is unstable and poor backlight is easily caused are effectively solved by optimizing selective matching and additive amount control of the complexing agent, the stabilizing agent and the reducing agent in the copper deposition composition, and the system is simple in component, low in cost and easy to popularize. And large-scale industrial popularization and application are easy to realize.

Description

Technical Field

[0001] The present invention relates to the technical field of electroless copper plating compositions, and specifically to an electroless copper plating composition and an electroless copper plating process. Background Art

[0002] The hole metallization of printed circuit boards (PCBs) is one of the core processes in PCB manufacturing. Its main function is to form a conductive film by depositing metallic copper or adsorbing conductive substances to achieve electrical connection between layers. Currently, the most mature hole metallization is achieved by electroless copper plating to deposit metallic copper on the substrate, preparing for the electrical conduction of subsequent electroplating. In existing electroless copper plating compositions, a concentrated palladium solution is used as the activator to achieve copper deposition, which not only increases cost pressure but also has quality problems such as poor backlight, and it is difficult to effectively balance the electroless copper plating rate and stability. Chinese Patent (authorization publication number: CN113463074 B) discloses an electroless copper plating composition and an electroless copper plating method, which overcome the defects during the electroless copper plating process and improve the mechanical properties of the electroless copper plating layer by optimizing the selection and combination of stabilizers and surfactants in the electroless copper plating solution. However, the system has complex components and is not easy to be popularized and applied on a large scale in industrial production. Summary of the Invention

[0003] To solve the above problems, the present invention provides an electroless copper plating composition and an electroless copper plating process. By optimizing the selection, combination and addition amount control of complexing agents, stabilizers and reducing agents in the electroless copper plating composition, the problems of unstable electroless copper plating bath and easy poor backlight in the market are effectively solved, and the system has simple components and is easy to be popularized and applied on a large scale in industrial production.

[0004] On the one hand, the present invention provides an electroless copper plating composition, which at least includes: a copper ion source, a complexing agent, a stabilizer, a reducing agent, an alkaline regulator, and a solvent; wherein, the stabilizer is selected from at least one of 2,2'-bipyridine, potassium selenocyanate, potassium thiocyanate or 2-mercaptobenzimidazole.

[0005] In one embodiment, the stabilizer is selected from one of 2,2'-bipyridine, potassium selenocyanate or 2-mercaptobenzimidazole.

[0006] In one embodiment, the content of the stabilizer in the electroless copper plating composition is 10 - 100 mg / L.

[0007] In one embodiment, the content of the stabilizer in the electroless copper plating composition is 30 - 80 mg / L.

[0008] In one embodiment, the copper ion source is copper sulfate or copper chloride.

[0009] In one embodiment, the content of the copper ion source in the electroless copper plating composition is 1 - 3 g / L.

[0010] In one embodiment, the content of the copper ion source in the copper deposition composition is 1.5 - 2.5 g / L.

[0011] In one embodiment, the complexing agent is EDTA tetrasodium (ethylenediaminetetraacetic acid tetrasodium), potassium sodium tartrate, or a combination of EDTA tetrasodium and potassium sodium tartrate.

[0012] In one embodiment, the mass ratio of EDTA tetrasodium to potassium sodium tartrate is (1 - 3):1.

[0013] In one embodiment, the content of the complexing agent in the copper deposition composition is 30 - 45 g / L.

[0014] In one embodiment, the content of the complexing agent in the copper deposition composition is 40 g / L.

[0015] In one embodiment, the reducing agent is selected from formaldehyde and its derivatives.

[0016] In one embodiment, the reducing agent is formaldehyde.

[0017] In one embodiment, the content of the reducing agent in the copper deposition composition is 2 - 6 g / L.

[0018] In one embodiment, the content of the reducing agent in the copper deposition composition is 3 - 5 g / L.

[0019] In one embodiment, the basicity regulator is selected from sodium hydroxide or potassium hydroxide.

[0020] In one embodiment, the basicity regulator is sodium hydroxide.

[0021] In one embodiment, the content of the basicity regulator in the copper deposition composition is 8 - 12 g / L.

[0022] In one embodiment, the solvent is water.

[0023] On the other hand, the present invention provides a chemical copper deposition process, which at least includes the following steps: preparing a copper deposition composition; pre-treating a substrate; and chemically depositing copper.

[0024] In one embodiment, the preparation of the copper deposition composition includes the following steps: stirring and mixing a copper ion source, a complexing agent, a stabilizer, a reducing agent, a basicity regulator, and a solvent.

[0025] In one embodiment, the pre-treatment of the substrate includes the following steps: successively subjecting the substrate to degreasing treatment, micro-etching treatment, and activation treatment.

[0026] In one embodiment, the substrate is an FR-4 copper clad laminate (epoxy glass cloth substrate).

[0027] In one embodiment, the degreasing treatment is as follows: using a degreasing agent, treating the substrate at 40 - 60°C for 2 - 5 minutes for degreasing.

[0028] In one embodiment, the degreasing agent is L - 109AS, sourced from Dongguan Biliang Cleaning Technology Co., Ltd.

[0029] In one embodiment, the micro - etching treatment is as follows: placing the degreased substrate in an aqueous sodium persulfate solution for micro - etching for 20 - 40 seconds.

[0030] In one embodiment, the concentration of the aqueous sodium persulfate solution is 2 - 8 wt%.

[0031] In one embodiment, the activation treatment is as follows: using a palladium chloride activation solution, treating the micro - etched substrate at 35 - 45°C for 1 - 3 minutes for activation.

[0032] In one embodiment, the palladium chloride activation solution is composed of palladium chloride and water, and the concentration of palladium chloride is 0.05 - 0.15 g / L.

[0033] In one embodiment, the electroless copper plating includes the following conditions: dipping time is 8 - 15 minutes; copper plating temperature is 40 - 50°C; mechanical stirring rate is 100 - 300 rpm.

[0034] By introducing 2,2 - bipyridine, potassium selenocyanate or 2 - mercaptobenzimidazole, and controlling the addition amounts of the complexing agent and the reducing agent, the provided copper - plating composition has excellent copper - plating rate, copper - plating uniformity, backlight defect rate and surface roughness simultaneously. In particular, by controlling the addition amount of EDTA - tetrasodium or sodium potassium tartrate in the system to be 30 - 45 g / L, the problems of missing plating and increased roughness are effectively avoided, and the surface quality of the formed copper - plating layer is ensured. Further, by controlling the addition amount of formaldehyde in the system to be 2 - 6 g / L, the copper - plating rate during the electroless copper - plating process and the compactness and surface finish of the copper - plating layer after copper - plating are effectively balanced, and the yield of PCB products is improved.

[0035] The copper - plating composition provided by the present invention does not require additional addition of various surfactants and copper - plating accelerators, greatly reducing the raw material cost of the copper - plating solution. The copper - plating rate is maintained at 0.35 - 0.42 μm / 10 min, and it is particularly suitable for horizontal production lines.

[0036] Beneficial effects

[0037] 1. The present invention provides a copper deposition composition and a chemical copper deposition process. By optimizing the selection and combination of complexing agents, stabilizers, and reducing agents in the copper deposition composition and controlling the addition amounts thereof, the problems of instability of the copper deposition tank in the market and easy poor backlight are effectively solved, and the system components are simple, making it easy to achieve large-scale industrial popularization and application.

[0038] 2. The present invention introduces 2,2'-bipyridine, potassium selenocyanate, or 2-mercaptobenzimidazole, and controls the addition amounts of the complexing agent and the reducing agent, so that the provided copper deposition composition has excellent copper deposition rate, copper deposition uniformity, poor backlight rate, and surface roughness at the same time.

[0039] 3. The present invention controls the addition amount of tetrasodium EDTA or potassium sodium tartrate in the system to be 30 - 45 g / L, effectively avoiding the problems of missing plating and rising roughness, and ensuring the surface quality of the formed copper deposition layer.

[0040] 4. The present invention controls the addition amount of formaldehyde in the system to be 2 - 6 g / L, effectively balancing the copper deposition rate in the chemical copper deposition process and the compactness and surface smoothness of the copper deposition layer after copper deposition, and improving the yield rate of PCB products.

[0041] 5. The copper deposition composition provided by the present invention does not require additional addition of various surfactants and copper deposition accelerators, greatly reducing the raw material cost of the copper deposition solution. The copper deposition rate is maintained at 0.35 - 0.42 μm / 10 min, and it is particularly suitable for horizontal production lines. Specific Embodiments

[0042] Examples 1 - 3, Comparative Examples 1 - 3

[0043] Examples 1 - 3 and Comparative Examples 1 - 3 of the present invention provide a copper deposition composition on the one hand, and the formula is shown in Table 1.

[0044] Table 1

[0045]

[0046] Example 1 of the present invention provides a copper deposition process on the other hand, including the following steps: preparing the copper deposition composition; pre-treating the substrate; chemically depositing copper.

[0047] The preparation of the copper deposition composition includes the following steps: stirring and mixing a copper ion source, a complexing agent, a stabilizer, a reducing agent, a basic regulator, and a solvent.

[0048] The pre-treatment of the substrate includes the following steps: sequentially subjecting the substrate to degreasing treatment, micro-etching treatment, and activation treatment. The substrate is an FR-4 copper clad laminate (epoxy glass cloth substrate). The degreasing treatment is: using a degreasing agent to perform degreasing treatment on the substrate at 50°C for 3 min. The degreasing agent is L-109AS, sourced from Dongguan Biliang Cleaning Technology Co., Ltd.

[0049] The micro-etching treatment is as follows: The substrate after degreasing treatment is placed in an aqueous solution of sodium persulfate for micro-etching treatment for 30 s. The concentration of the aqueous solution of sodium persulfate is 5 wt%.

[0050] The activation treatment is as follows: Using a palladium chloride activation solution, at a temperature of 40 °C, the substrate after micro-etching treatment is subjected to activation treatment for 2 min. The palladium chloride activation solution is composed of palladium chloride and water, and the concentration of palladium chloride is 0.1 g / L.

[0051] The electroless copper plating includes the following conditions: The impregnation time is 10 min; the copper plating temperature is 45 °C; the mechanical stirring rate is 200 rpm.

[0052] On the other hand, Example 2 of the present invention provides an electroless copper plating process, and its specific implementation manner is the same as that of Example 1, except that the conditions of the electroless copper plating are replaced with: the impregnation time is 15 min; the copper plating temperature is 50 °C; the mechanical stirring rate is 100 rpm.

[0053] On the other hand, Example 3 of the present invention provides an electroless copper plating process, and its specific implementation manner is the same as that of Example 1, except that the conditions of the electroless copper plating are replaced with: the impregnation time is 8 min; the copper plating temperature is 40 °C; the mechanical stirring rate is 300 rpm.

[0054] On the other hand, Comparative Examples 1-3 of the present invention provide an electroless copper plating process, and its specific implementation manner is the same as that of Example 1.

[0055] Performance test

[0056] Test the copper plating rate, copper plating uniformity, backlight defect rate and surface roughness of the electroless copper plating compositions provided in the test examples and comparative examples. The test reference methods and test results are shown in Table 2.

[0057] Table 2

[0058]

[0059] It can be seen from the data in Table 2 that, compared with Comparative Examples 1-3, the electroless copper plating compositions provided in Examples 1-3 significantly improve the copper plating rate, uniformity and surface quality, and better meet the actual application requirements.

Claims

1. A copper deposition composition, characterized in that: At least: Copper ion source, complexing agent, stabilizer, reducing agent, alkaline regulator, solvent; wherein the stabilizer is selected from at least one of 2-2-bipyridine, potassium selenocyanate, potassium thiocyanide or 2-mercaptobenzimidazole.

2. The copper deposition composition according to claim 1, characterized in that: The content of the complexing agent in the copper deposition composition is 30-45 g / L.

3. The copper deposition composition according to claim 1, characterized in that: The content of the reducing agent in the copper deposition composition is 2-6 g / L.

4. The copper deposition composition according to claim 1, characterized in that: The stabilizer is selected from one of 2-2-bipyridine, potassium selenocyanate and 2-mercaptobenzimidazole.

5. The copper deposition composition according to claim 1, characterized in that: The content of the stabilizer in the copper deposition composition is 10-100 mg / L.

6. The copper deposition composition according to claim 1, characterized in that: The complexing agent is EDTA-tetrasodium, potassium sodium tartrate or a combination of EDTA-tetrasodium and potassium sodium tartrate.

7. The copper deposition composition according to claim 1, characterized in that: The reducing agent is selected from formaldehyde and its derivatives.

8. A chemical copper deposition process using the copper deposition composition according to any one of claims 1 to 7, characterized in that: At least the following steps are included: preparing a copper deposition composition; Substrate pretreatment; chemical copper deposition.

9. The chemical copper deposition process according to claim 8, characterized in that: The substrate pretreatment comprises the following steps: subjecting the substrate to degreasing treatment, micro-etching treatment and activation treatment in sequence.

10. The chemical copper deposition process according to claim 8, characterized in that: The chemical copper deposition includes the following conditions: the immersion time is 8-15 minutes; the copper deposition temperature is 40-50° C.; and the mechanical stirring rate is 100-300 rpm.

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