Cyanide-free tinning electroplating solution and preparation method thereof

Abstract

The invention relates to a cyanide-free tinning electroplating solution and a preparation method thereof, the cyanide-free tinning electroplating solution mainly comprises stannous methanesulfonate, methanesulfonic acid, a composite brightener, electroplating gelatin, an antioxidant, a surfactant, a complexing agent and the like, and the composite brightener is composed of a brightener I and a brightener II. Through a specific preparation process, all the components are sequentially added into deionized water and uniformly stirred, and the uniform and transparent electroplating liquid is obtained. The electroplating liquid can effectively improve the adhesive force of a plating layer and a base material, forms the plating layer with excellent corrosion resistance and good conductivity and weldability, does not contain cyanogen and vanadium compounds, and meets the environmental protection requirement. The electroplating liquid is suitable for a tin plating process of a base material under most conditions, the practical range is wide, the adhesive force of a coating and the base material can be remarkably enhanced, the corrosion resistance of the coating is improved, it is guaranteed that the surface of an electroplated layer is smooth and high in glossiness, and the good appearance and the good anti-corrosion effect are achieved.

Description

Technical Field

[0001] The invention relates to the field of electronic packaging tinning tinning solution, and in particular to a cyanide-free tinning electroplating solution and a preparation method thereof. Background Art

[0002] At present, integrated circuit products tend to develop towards high performance, high integration and high reliability, and correspondingly, semiconductor electronic devices are gradually developing towards integration, high efficiency and safety. With the continuous improvement of packaging technology, the size of packaged products is getting smaller and smaller, and it is becoming more and more difficult to protect their surfaces. Therefore, it is necessary to improve the electroplating process, and people also put forward higher requirements on the characteristics of tin plating solution.

[0003] Tin can further enhance the conductivity and solderability of electronic components and improve the reliability of electronic components due to its excellent corrosion resistance. At present, ordinary electroplating solutions have the characteristic of poor adhesion to the substrates in electronic components, which makes the coating easy to fall off. At the same time, due to the unstable concentration of additives, salts and other components in the plating solution, it is easy to cause uneven coating formation or color difference. In addition, since the additives in the electroplating solution often contain cyanide stannates, vanadium antioxidants, etc., it also poses great challenges to the health of operators and environmental protection performance. Therefore, the development of a tin-plating electroplating solution with stable additives and salts, good adhesion to the substrate, excellent corrosion resistance of the coating itself, and good conductivity and solderability has become the key to solving the coating problem. Summary of the invention

[0004] The object of the present invention is to provide a cyanide-free tin plating solution and a preparation method thereof, wherein a certain component of electroplating gelatin, an antioxidant, a surfactant and other plating solution additives are added, which can effectively improve the adhesion between the plating solution and the substrate, and form a coating with excellent anti-corrosion performance, good conductivity and good weldability. At the same time, the additive does not contain cyanide and vanadium compounds, which meets environmental protection requirements.

[0005] The objective of the present invention is achieved through the following technical solutions: A cyanide-free tin plating solution comprising the following components in the following concentrations: Stannous methanesulfonate 0.3~0.8 mol / L Methanesulfonic acid 0.5~1.2 mol / L Composite brightener 0.06~0.3 mol / L Electroplating gelatin 0.5~6 g / L Antioxidant 1~8 g / L Surfactant 1~10g / L Complexing agent 2~15g / L.

[0006] In the above tin plating solution, the composite brightener includes a brightener and brightener ; Among them, brightener The concentration is 0.05~0.2 mol / L, brightener The concentration is 0.01~0.1 mol / L.

[0007] The brightener One or more selected from benzoic acid, p-toluic acid, p-hydroxybenzoic acid, terephthalic acid and their sulfonic acid group, nitro group, amino group substitutes.

[0008] The brightener One or more selected from orthophosphoric acid, metaphosphoric acid and metal salt compounds thereof.

[0009] The electroplated gelatin is animal glue, specifically a type of chain-like high-molecular protein with a molecular weight between 3000 and 100000 and is soluble in water.

[0010] The antioxidant is one or more mixtures of methylphenols, methylphenols and phenol substitutes.

[0011] The surfactant is a mixture of one or more of polyethylene glycol, isopropanolamine, sodium lauryl sulfate and gluconolactone.

[0012] The complexing agent is a mixture of one or more of glycolic acid, ethylenediaminetetraacetic acid and citric acid amine.

[0013] A method for preparing the above-mentioned cyanide-free tin plating solution is specifically: In deionized water, add methanesulfonic acid with stirring, and continue to add stannous methanesulfonate while stirring. After stirring evenly, add brightener in sequence. , Brightener , electroplating gelatin, antioxidant, surfactant and complexing agent, stir evenly to obtain a uniform and transparent liquid.

[0014] The advantages and effects of the present invention are: 1. In the electroplating solution provided by the present invention, the added composite brightener is easily soluble in the plating solution and can significantly enhance the 2+ The chelating and coordination effect can make the surface of the electroplating layer smooth and glossy, achieving good appearance and anti-corrosion effect.

[0015] 2. A small amount of gelatin added to the electroplating solution provided by the present invention can significantly enhance the adhesion between the coating and the substrate, while improving the corrosion resistance of the coating.

[0016] 3. The electroplating solution provided by the present invention is suitable for the tin-plating process of substrates in most cases and has a wide range of practical applications. DETAILED DESCRIPTION

[0017] The present invention is described in detail below with reference to the embodiments.

[0018] Example 1 Add 1L of deionized water to a beaker, add 0.5mol of methanesulfonic acid while stirring, continue to add 0.3mol of stannous methanesulfonate while stirring, stir evenly, then add 0.05mol of benzoic acid, 0.01mol of metaphosphoric acid, 2.0g of gelatin, 3.5g of p-methylphenol, 2.2g of sodium dodecyl sulfate and 4.5g of diammonium citrate in sequence, stir evenly to obtain a uniform and transparent liquid.

[0019] Example 2 Add 1L of deionized water to a beaker, add 0.55mol of methanesulfonic acid while stirring, continue to add 0.25mol of stannous methanesulfonate while stirring, stir evenly, then add 0.08mol of p-toluic acid, 0.03mol of phosphoric acid, 2.5g of gelatin, 4.2g of 2,4-di-tert-butylphenol, 3.5g of isopropanolamine and 5.2g of gluconolactone in sequence, stir evenly to obtain a uniform transparent liquid.

[0020] Example 3 Add 1L of deionized water to a beaker, add 0.45mol of methanesulfonic acid while stirring, continue to add 0.20mol of stannous methanesulfonate while stirring, stir evenly, then add 0.08mol of p-hydroxybenzoic acid, 0.03mol of phosphoric acid, 1.8g of gelatin, 4.5g of 2,4,6-di-tert-butylphenol, 4.2g of PEG (3000) and 6.5g of diammonium citrate in sequence, stir evenly to obtain a uniform and transparent liquid.

[0021] Composite brightener including brightener and brightener Its function is to increase the cathode polarization by chelating and coordinating with metal ions, while preventing the adsorption of impurities such as hydrogen, ensuring the stability of the electroplating solution, making the surface of the electroplating layer smooth and glossy, achieving good appearance and anti-corrosion effects, and improving the quality of electroplating.

[0022] The electroplating solution prepared by the present invention can significantly enhance the adhesion between the coating and the substrate, making the coating more solid and less likely to peel off. In addition, gelatin itself has good air permeability and moisture retention to prevent oxidants, can effectively prevent oxidation and corrosion of the coating surface, and improve the corrosion resistance of the coating.

Claims

1. A cyanide-free tin plating solution, characterized in that Contains the following components in the following concentrations: Stannous methanesulfonate 0.3~0.8 mol / L Methanesulfonic acid 0.5~1.2 mol / L Composite brightener 0.06~0.3 mol / L Electroplating gelatin 0.5~6 g / L Antioxidant 1~8 g / L Surfactant 1~10g / L Complexing agent 2~15 g / L.

2. A cyanide-free tin plating solution according to claim 1, characterized in that: In the above tin plating solution, the composite brightener includes a brightener and brightener ; Among them, brightener The concentration is 0.05~0.2 mol / L, brightener The concentration is 0.01~0.1 mol / L.

3. A cyanide-free tin plating solution according to claim 2, characterized in that: The brightener One or more selected from benzoic acid, p-toluic acid, p-hydroxybenzoic acid, terephthalic acid and their sulfonic acid group, nitro group, amino group substitutes.

4. A cyanide-free tin plating solution according to claim 2, characterized in that: The brightener One or more selected from orthophosphoric acid, metaphosphoric acid and metal salt compounds thereof.

5. A cyanide-free tin plating solution according to claim 1, characterized in that: The electroplated gelatin is animal glue, specifically a type of chain-like high-molecular protein with a molecular weight between 3000 and 100000 and is soluble in water.

6. A cyanide-free tin plating solution according to claim 1, characterized in that: The antioxidant is one or more mixtures of methylphenols, methylphenols, and phenol substitutes.

7. A cyanide-free tin plating solution according to claim 1, characterized in that: The surfactant is a mixture of one or more of polyethylene glycol, isopropanolamine, sodium lauryl sulfate and gluconolactone.

8. A cyanide-free tin plating solution according to claim 1, characterized in that: The complexing agent is a mixture of one or more of glycolic acid, ethylenediaminetetraacetic acid and citric acid amine.

9. A method for preparing a cyanide-free tin plating solution as claimed in claim 1, characterized in that: Specifically: In deionized water, add methanesulfonic acid with stirring, and continue to add stannous methanesulfonate while stirring. After stirring evenly, add brightener in sequence. , Brightener , electroplating gelatin, antioxidant, surfactant and complexing agent, stir evenly to obtain a uniform and transparent liquid.