A copper plating solution and stabilizer

Abstract

The application provides a copper plating solution and a stabilizer, which comprises copper sulfate pentahydrate, a complexing agent, formaldehyde, ethanolamine, 2,2-bipyridine, S-adenosyl-L-homocysteine, S-carboxymethyl-L-cysteine and thiomalic acid. The S-adenosyl-L-homocysteine and the S-carboxymethyl-L-cysteine can improve the tolerance of the plating solution to leached palladium. After a certain amount of thiomalic acid is added, the three components have a good synergistic effect. The plating solution maintains high activity and further improves the tolerance to leached palladium, which is beneficial to improve the service life of the plating solution and prolong the decomposition time of the plating solution. Even under high leached palladium concentration, the thick copper solution does not affect the plating activity and the uniform plating capacity of the chemical copper plating solution. Under normal production load, a deposition rate of 1.0 um / 20 min can be obtained. The solution has good stability. Under extreme conditions of high leached palladium, the decomposition time of the plating solution is prolonged by 2-6 hours.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of copper plating solution, in particular to a copper plating solution and a stabilizer. BACKGROUND

[0002] PCB chemical thick copper plating is a process of chemical copper deposition in hole metallization. Chemical copper deposition (also known as chemical copper plating) is roughly divided into thin copper deposition (deposition rate is about 0.3-0.5 μm / cycle), medium copper deposition (deposition thickness is about 0.6-0.9 μm / cycle) and thick copper deposition (deposition thickness is about 0.9-1.2 μm / cycle) according to the deposition thickness. After thin copper deposition and medium copper deposition, a thin copper layer is needed to be electroplated before pattern making, and after thick copper deposition, the processes of film pasting, exposure, development and etching can be directly performed to form a pattern. Compared with thin copper deposition and medium copper deposition, thick copper deposition reduces the process of full-plate electroplating of a thin copper layer and reduces the cost.

[0003] The process flow of PCB thick copper deposition is swelling, glue removal, neutralization, oil removal, micro-etching, pre-impregnation, activation, acceleration and copper deposition. Chemical copper plating is a key process of chemical copper deposition of a circuit board and is important for hole metallization in the process of manufacturing a PCB. The thickness of a chemical plating layer meeting the standard is a quality guarantee for pattern making in the subsequent process.

[0004] After the circuit board is adsorbed with colloidal palladium in the activation tank and then is de-glued in the acceleration tank, the palladium core adsorbed on the inner wall of the hole of the circuit board is exposed, so that the palladium core can be used as a catalytic core for copper deposition in the copper deposition tank. After each batch of circuit board material enters the copper deposition tank, the palladium core catalyzes copper deposition on the hole wall base plate.

[0005] However, the exposed palladium in the hole is immersed, peeled off and diffused to the copper deposition solution to a certain extent. With the increase of the number of batches (quantity) of the circuit board, the palladium content in the copper deposition solution accumulates to a certain concentration, a plurality of catalytic active sites are formed in the plating solution, the plating solution is catalyzed to precipitate nano-sized copper particles, the copper particles continue to catalyze the copper deposition solution as a catalytic core to form a chain reaction, copper is deposited on the surface of the copper particles, which leads to the decrease of the stability of the copper deposition solution, and finally leads to the precipitation of large copper particles in the plating solution during the copper deposition process, which is deposited on the tank wall and in the plating solution, and seriously affects the service life of the chemical copper plating solution. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a copper plating solution and a stabilizer, so as to ensure that the high deposition rate reaches the thick copper standard while having stable performance and promoting production efficiency.

[0007] The technical scheme of the present application is a copper plating solution which can reach 0.9-1.2 μm / 20 min and comprises the following components:

[0008] Basic copper plating solution:

[0009] Copper sulfate pentahydrate 8-12 g / L;

[0010] Complexing agent 26-34 g / L;

[0011] Formaldehyde 5-7 ml / L;

[0012] Ethanolamine 1.5-2.5 mg / L;

[0013] 2,2'-Bipyridine 1-3 mg / L;

[0014] Stabilizer:

[0015] S-Adenosyl-L-homocysteine (I) 0.01-30 ppm;

[0016] S-Carboxymethyl-L-cysteine (II) 0.05-20 ppm;

[0017] Thiomalic acid (III) 0.05-20 ppm.

[0018] As a preferred, the complexing agent is potassium sodium tartrate.

[0019] As a preferred, the amount of copper sulfate pentahydrate is 10 g / L, the amount of potassium sodium tartrate is 30 g / L; the amount of formaldehyde is 6 ml / L; the amount of ethanolamine is 2 mg / L; the amount of 2,2'-bipyridine is 2 mg / L.

[0020] As a preferred, the mass ratio of S-Adenosyl-L-homocysteine (I), S-Carboxymethyl-L-cysteine (II), and Thiomalic acid (III) is 1:(0.1-5):(0.1-2).

[0021]

[0022] As a preferred, the content of S-Adenosyl-L-homocysteine (I) is 1-30 ppm.

[0023] As a preferred, the content of S-Carboxymethyl-L-cysteine (II) is 0.1-1 ppm.

[0024] As a preferred, the content of Thiomalic acid (III) is 0.5-2 ppm.

[0025] As a preferred, the pH of the copper plating solution for copper plating is 12.5, and the deposition rate is 0.9-1.2 μm / 20 min.

[0026] ​As preferred, the present application further provides a stabilizer, comprising S-adenosyl-L-homocysteine (I); S-carboxymethyl-L-cysteine (II); thiomalic acid (III); wherein the mass ratio of the S-adenosyl-L-homocysteine (I), S-carboxymethyl-L-cysteine (II), thiomalic acid (III) is 1: (0.1-5): (0.1-2).

[0027] As preferred, the content of the S-adenosyl-L-homocysteine (I) is 0.01-30 ppm;

[0028] The content of the S-carboxymethyl-L-cysteine (II) is 0.05-20 ppm;

[0029] The content of the thiomalic acid (III) is 0.05-20 ppm.

[0030] The present application has the following beneficial effects:

[0031] 1. The S-adenosyl-L-homocysteine and S-carboxymethyl-L-cysteine of the present application can improve the tolerance of the plating solution to leached palladium, and after adding a certain amount of thiomalic acid, the three have good synergistic effect, the plating solution maintains high activity while the tolerance to leached palladium is further enhanced, which is conducive to improving the service life of the plating solution and prolonging the decomposition time of the plating solution;

[0032] 2. The thick copper plating solution of the present application will not affect the plating activity and leveling ability of the chemical copper plating solution even under high leached palladium concentration, and under normal production load, a deposition rate of 1.0 μm / 20 min can be obtained.

[0033] 3. The thick copper plating solution of the present application has good stability, and under the extreme condition of high leached palladium, the decomposition time of the plating solution is prolonged by 2-6 hours, which ensures the service life of the chemical plating solution and reduces the production cost. DETAILED DESCRIPTION

[0034] The specific embodiments of the present application are further described below:

[0035] Examples 1-8

[0036] The following examples use copper sulfate pentahydrate, potassium sodium tartrate, sodium hydroxide, formaldehyde, ethanolamine, and 2,2-dipyridyl as the basic components of the thick copper plating solution, and on this basis, whether to add the stabilizer forms Examples 1-8 and Comparative Example 1. The copper plating performance is analyzed.

[0037] The tolerance of the electroless plating solution to palladium is tested by adding activated palladium to the electroless plating solution, and the stability of the electroless plating solution is determined by the decomposition time of the electroless plating solution under the same amount of palladium addition, and the longer the tolerance time is, the stronger the tolerance of the electroless plating solution to palladium is, that is, the better the stability of the electroless plating solution is.

[0038] The deposition rate of the electroless plating solution is determined by a deposition rate sheet to confirm the deposition activity of the electroless plating solution, and the deposition speed.

[0039] The plating copper solution compositions of Examples 1-8 and Comparative Example 1 are shown in Table 1.

[0040] The test temperature is 42°C, and the timing starts from the test plate being put into the plating solution, and the timing ends when the entire surface of the test plate is attached with a copper layer, which is recorded as the copper plating start time; the test plate is taken out after electroless copper plating for 20 minutes, a section is ground and cut, the back light condition is observed by a metallographic microscope and rated, and the deposition rate of the electroless copper plating is determined by the test sheet; the plating solution after copper plating is left to stand, the decomposition of the plating solution is observed, the decomposition time is recorded, and the stability of the electroless plating solution is evaluated, and the experimental results are shown in Table 2.

[0041] Table 1 Plating copper solution compositions of Examples 1-8 and Comparative Example 1

[0042]

[0043] Table 2 Experimental results of Examples 1-8 and Comparative Example 1

[0044]

[0045] According to the results of Examples 1-8 and Comparative Example 1, the electroless plating solution without the addition of the stabilizers S-adenosyl-L-homocysteine, S-carboxymethyl-L-cysteine and thiomalic acid in the application rapidly decomposes, has poor stability, and the surface of the test sheet is dark red.

[0046] In Examples 1-8 and Comparative Example 1, 1 ppm of activated palladium is added respectively to simulate the palladium leaching in the production process, and the tolerance degree and the decomposition time of the plating solution after the addition of palladium are investigated. The timing starts from the addition of palladium, the time of the beginning of decomposition (copper powder precipitation) is recorded, and the timing stops when the plating solution completely decomposes (all copper in the plating solution is precipitated), and the results are shown in Table 3.

[0047] Table 3 Palladium tolerance degree test results of Examples 1-8 and Comparative Example

[0048]

[0049] According to the palladium tolerance degree test results in Table 3, the palladium tolerance degree of Examples 1-8 after the addition of the combined additive is higher than that of Comparative Example 1, and the decomposition time is longer.

[0050] The foregoing embodiments and description of the application only illustrate the principle and the best mode of the application, and various changes and modifications can be made to the application without departing from the spirit and scope of the application, and all these changes and modifications fall within the scope of the application.

Claims

1. A copper plating solution, characterized by comprising: It comprises the following components: A base copper plating solution: Copper sulfate pentahydrate 8-12 g / L; Complexing agent 26-34 g / L; 37% formaldehyde 5-7 ml / L; Ethanolamine 1.5-2.5 mg / L; 2,2-dipyridyl 1-3 mg / L; Stabilizer: S-adenosyl-L-homocysteine (I) 0.01-30 ppm; S-carboxymethyl-L-cysteine (II) 0.05-20 ppm; Thiomalic acid (III) 0.05-20 ppm; The mass ratio of the S-adenosyl-L-homocysteine (I), S-carboxymethyl-L-cysteine (II), and thiomalic acid (III) is 1:(0.1-0.3):0.

5.

2. The copper plating solution of claim 1, wherein: The complexing agent is potassium sodium tartrate.

3. The copper plating solution of claim 2, wherein: The amount of copper sulfate pentahydrate is 10 g / L, the amount of potassium sodium tartrate is 30 g / L; the amount of formaldehyde is 6 ml / L; the amount of ethanolamine is 2 mg / L; the amount of 2,2-dipyridyl is 2 mg / L.

4. The copper plating solution of claim 1, wherein: The content of S-adenosyl-L-homocysteine (I) is 1-30 ppm.

5. The copper plating solution of claim 1, wherein: The content of S-carboxymethyl-L-cysteine (II) is 0.1-1 ppm.

6. The copper plating solution of claim 1, wherein: The content of thiomalic acid (III) is 0.5-2 ppm.

7. The copper plating solution of claim 1, wherein: The pH of the copper plating solution for copper plating is 12.5, and the deposition rate is 0.9-1.2 μm / 20 min.

8. A stabilizer for the copper plating solution according to any one of claims 1 to 7, characterized in that: It comprises S-adenosyl-L-homocysteine (I); S-carboxymethyl-L-cysteine (II); thiomalic acid (III); wherein the mass ratio of the S-adenosyl-L-homocysteine (I), S-carboxymethyl-L-cysteine (II), and thiomalic acid (III) is 1:(0.1-5):(0.1-2).

9. The stabilizing agent of claim 8, wherein: The content of S-adenosyl-L-homocysteine (I) is 0.01-30 ppm; The content of S-carboxymethyl-L-cysteine (II) is 0.05-20 ppm; The content of thiomalic acid (III) is 0.05-20 ppm.

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