Environmental-friendly solution capable of inhibiting generation rate of tetravalent tin

Abstract

The invention discloses an environmental-friendly solution capable of inhibiting the generation rate of tetravalent tin. The solution is prepared from the following components according to the concentration: 10 to 30g / L of stannous ion, 70 to 130g / L of thiourea, 30 to 70g / L of methanesulfonic acid, 10 to 50mg / L of interfacial agent, 30 to 60g / L of sodium hexametaphosphate, 20 to 30g / L of ethylenediamine tetra sodium, 10 to 30g / L of sodium oxalate, 0 to 10g / L of cysteine, and 0 to 20g / L of ascorbic acid. The components are uniformly mixed so as to be prepared into a chemical solution; and thechemical solution has the characteristics that under the conditions of ensuring the good stability of the solution and the stable tin deposition rate, the rate for oxidizing divalent tin into the tetravalent tin is effectively inhibited, and substances and byproducts contained in the formula are safe, environmental-friendly and friendly to the environment. According to the environmental-friendly solution capable of inhibiting the generation rate of the tetravalent tin provided by the invention, multiple complexing agents are contained in the formula, the stannous ions cannot be easily oxidizedinto the tetravalent tin, and the oxidation of oxygen dissolved in a plating solution on the stannous ions can be removed by utilizing a reducing agent.

Description

technical field [0001] The invention relates to the technical field of circuit boards, in particular to an environment-friendly solution capable of suppressing the generation rate of tetravalent tin. Background technique [0002] Printed circuit board, also known as PCB circuit board, is the provider of electrical connection for electronic components. Printed circuit boards have developed from single-layer to double-sided, multi-layer and flexible boards, and are constantly developing in the direction of high precision, high density and high reliability. Continuous reduction in size, cost reduction, and performance improvement enable printed circuit boards to maintain strong vitality in the development of future electronic products. [0003] The future development trend of printed circuit board manufacturing technology is to develop in the direction of high density, high precision, fine aperture, thin wire, small pitch, high reliability, multi-layer, high-speed transmission...

AI Technical Summary

Problems solved by technology

[0004] The surface treatment in the circuit board field mainly refers to the final treatment of the copper surface. The treated surface can perform functions such as welding and binding. In this field, developed countries have been at the forefront. In recent years, OSP, chemical nickel and gold It has developed to a certain extent in China, but OSP finished product inspection is not convenient for visual inspection and electrical measurement, SMT rework is not suitable, and storage conditions are required.

Electroless nickel gold has the disadvantages of nickel corrosion, easy permeation plating, missing plating, etc.

[0005] Chemically pure tin coating has long been used in the field of surface treatment of automotive circuit boards or IC substrates, thanks to its many advantages, such as good flatness of the tin surface, excellent electrical conductivity and solderability, and can be used many times Soldering, the tin layer does not contain lead, has no pollution to the environment, the process is simple, and the working environment is good. However, the existing chemical tin plating solutions contain polymer complexing agents that are difficult to degrade, and because the Oxygen mixed into the plating solution causes the formation rate of tetravalent tin to be too fast, which affects the benefits and brings high costs

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