Surface treatment method for circuit board

Abstract

This invention discloses a surface treatment method for a circuit board, comprising: a cleaning step for cleaning the surface of the circuit board; an activation step for coating a catalyst on the surface of the circuit board; the catalyst forming a catalytic layer on the surface of the circuit board; a nickel plating step for immersing the circuit board in a nickel plating solution to perform chemical nickel plating and replacing the catalytic layer with a nickel layer; and a gold plating step for forming a thin gold layer on the nickel layer; wherein the nickel plating solution comprises a nickel source agent, a reducing agent, a stabilizer, and an accelerator, and based on a volume of 100 vol%, the nickel plating solution comprises 3 vol% to 7 vol% of the nickel source agent, 0.5 vol% to 3 vol% of the reducing agent, 0.5 vol% to 0.77 vol% of the stabilizer, and 0.1 vol% to 1 vol% of the accelerator; wherein the nickel source agent comprises nickel sulfate, the reducing agent comprises sodium hypophosphite, and the accelerator comprises sodium sulfate.

Claims

1. A surface treatment method for a circuit board, comprising: a cleaning step for cleaning the surface of a circuit board; an activation step for coating a catalyst on the surface of the circuit board; the catalyst forming a catalytic layer on the surface of the circuit board; a nickel plating step for chemically plating nickel onto the surface of the circuit board using a nickel plating solution to form a nickel layer; and an immersion gold step for forming a thin gold layer on the nickel layer; wherein, The nickel plating solution comprises a nickel source agent, a reducing agent, a stabilizer, and an accelerator. Based on a volume of 100 vol%, the nickel plating solution contains 3 vol% to 7 vol% of the nickel source agent, 0.5 vol% to 3 vol% of the reducing agent, 0.5 vol% to 0.77 vol% of the stabilizer, and 0.1 vol% to 1 vol% of the accelerator. The nickel source agent comprises nickel sulfate, the reducing agent comprises sodium hypophosphite, and the accelerator comprises sodium sulfate. Based on a total weight of 100 wt% of the accelerator, the sodium sulfate content is between 0.5 wt% and 2 wt%, with the remainder being water.

2. The surface treatment method for a circuit board as described in claim 1, wherein, The nickel source agent also contains organic hydroxy acids and water. Based on the total weight of the nickel source agent being 100 wt%, the content of nickel sulfate is between 40 wt% and 50 wt%, the content of organic hydroxy acids is between 1 wt% and 5 wt%, and the remainder is water.

3. The surface treatment method for a circuit board as described in claim 2, wherein, Organic hydroxy acids are at least one of lactic acid, citric acid, tartaric acid, malic acid, salicylic acid, or glycolic acid, or combinations thereof.

4. The surface treatment method for a circuit board as described in claim 1, wherein, The reducing agent also comprises an organic hydroxy acid and water, with the total weight of the reducing agent being 100 wt%, the content of sodium hypophosphite being between 45 wt% and 55 wt%, the content of organic hydroxy acid being between 5 wt% and 15 wt%, and the remainder being water.

5. The surface treatment method for a circuit board as described in claim 1, wherein, The stabilizer is composed of sodium hydroxide and water. Based on the total weight of the stabilizer being 100 wt%, the content of sodium hydroxide is between 10 wt% and 20 wt%, and the remainder is water.

6. The surface treatment method for a circuit board as described in claim 1, wherein, The nickel plating solution also includes an auxiliary agent, which is composed of ammonia solution, sodium hypophosphite, organic hydroxy acid, and water.

7. The surface treatment method for a circuit board as described in claim 6, wherein, Based on the total weight of the aforementioned auxiliary agents being 100 wt%, the content of ammonia solution is between 5 wt% and 15 wt%, the content of sodium hypophosphite is between 15 wt% and 25 wt%, the content of organic hydroxy acids is between 20 wt% and 30 wt%, and the remainder is water.

8. The surface treatment method for a circuit board as described in claim 1, wherein, The nickel ion concentration of the nickel plating solution is between 4.6 g / L and 5.2 g / L.

9. The surface treatment method for a circuit board as described in claim 1, wherein, The pH value of the nickel plating solution is between 5 and 6.

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