Lead-free electroless tin plating solution

Abstract

The invention relates to a lead-free electroless tin plating solution. The lead-free electroless tin plating solution is characterized by comprising the following components: 20 to 30g / L of stannous mono-sulphate, 60 to 120g / L of thiourea, 15 to 25g / L of citric acid, 20 to 50g / L of sulfur dioxide, 3 to 5g / L of ethylene diamine tetraacetic acid, 0.01 to 0.05g / L of polyethylene glycol, 20 to 55m / L of 98% of concentrated sulfuric acid, 0.5 to 1.0g / L of gelatin, and the balance of regulator. The lead-free electroless tin plating solution has the advantages that few categories of chemical materials are used and cost is low; the tin can be continuously deposited at a high speed on copper and a copper alloy substrate, thus semi-bright chemical coatings with different thicknesses can be produced, and the flatness of the chemical coatings can be improved; and the lead-free electroless tin plating solution is remarkable in grain refinement, low in porosity, simple in formula of plating solution, easy to control, stable in plating solution, long in service life and high in stability in batch production; and polyethylene glycol is a nontoxic and nonirritating substance with high water solubility, and can be combined with other materials without producing harmful substances.

Description

technical field [0001] The invention relates to a lead-free chemical tin plating solution. Background technique [0002] With the miniaturization of electronic products, since the tin-plated layer is a coating with good solderability and certain corrosion resistance, it is widely used in electronic wires and printed circuit boards. The tin-plated layer can be electroplated, dipped and chemically Plating method is prepared, immersion tin is easy to operate and low in cost, but the thickness of the coating is limited, generally only 0.5 μm, the plating solution is easily poisoned, and cannot meet industrial requirements. Electrolytic tin plating cannot process deep hole parts and blind hole parts. Electroless tin plating The thickness of the coating is uniform, the dispersion ability of the plating solution is good, the production efficiency is high, and the operation is easy to control. Electroless plating technology for electronic wires, but because tin has high hydrogen ev...

AI Technical Summary

Problems solved by technology

[0002] With the miniaturization of electronic products, since the tin-plated layer is a coating with good solderability and certain corrosion resistance, it is widely used in electronic wires and printed circuit boards. The tin-plated layer can be electroplated, dipped and chemically Plating method is prepared, immersion tin is easy to operate and low in cost, but the thickness of the coating is limited, generally only 0.5 μm, the plating solution is easily poisoned, and cannot meet industrial requirements. Electrolytic tin plating cannot process deep hole parts and blind hole parts. Electroless tin plating The thickness of the coating is uniform, the dispersion ability of the plating solution is good, the production efficiency is high, and the operation is easy to control. Electroless plating technology for electronic wires, but because tin has high hydrogen evolution potential and low catalytic activity, if formaldehyde, sodium hypophosphite, borohydride and other reducing agents are used alone, continuous self-catalytic deposition of tin cannot be achieved, and thicker coatings cannot be obtained. coating, therefore, in order to solve the above problems, a new technical solution is provided