Tin plating solution as well as preparation method and application thereof

Abstract

The invention relates to a tin plating solution as well as a preparation method and application thereof. The tin plating solution comprises the following components of 0.01-1 mol / L of a stannous ion source, 0.1-2 mol / L of methanesulfonic acid, 0-1.3 mol / L of boric acid, 0.2-5 mol / L of carboxylate, 0.02-2 mol / L of complexing agents and 0. 0001-0.01 mol / L of surfactant, and the pH value range of thetin plating solution is 3.5-5.5. The tin plating solution has the advantages that excellent current density bearing capacity is achieved, and the situation of 'sticking' and 'scorching' can be avoided under the condition of relatively high current density.

Description

technical field [0001] The invention relates to the field of preparation of printed circuit boards, in particular to tin plating solution and its preparation method and application. Background technique [0002] In the preparation process of electronic equipment, in order to improve the solderability of printed circuit boards or electronic components, tinning is usually performed on them. At present, with the development of miniaturization and integration of electronic equipment, the size of circuit boards and electronic components is also getting smaller and smaller. Therefore, when electroplating tin, due to the uneven distribution of current in the plating solution, the plating speed in the high current (near the cathode end) area is too fast, which may easily cause the electronic components to stick to each other and cause "sticking", resulting in product failure. The yield rate is extremely low. At the same time, when electroplating larger components or circuit boards...

AI Technical Summary

Problems solved by technology

According to reports, in order to obtain better current dispersing ability, some technicians add current dispersing agent containing unsaturated bonds in the molecule to the electroplating solution system to disperse the current density in the high position area, but such additives added will interact with tin ions Complexation affects the stability of the system and the efficiency of electroplating, and the added current dispersant is relatively special, which will increase the cost in actual production and is not conducive to industrialization

[0004] The problem of "burning" is closely related to the current density tolerance of the electroplating solution. At present, in order to obtain a better current density tolerance, the research and development personnel will use an acidic electroplating solution system, and will add a large amount of strong acid electrolyte. The pH value is generally lower than 2, but while obtaining better current density tolerance, it also has the following disadvantages: (1) The ceramic electrode is corroded because of too high acidity; (2) With the progress of electroplating, the hydrogen evolution is serious, and the current Efficiency drops, resulting in uneven tin layer on the surface of the plated parts, affecting the appearance. (3) As the electroplating progresses, the system becomes unstable, and stannous ions are easily oxidized, and additional antioxidants need to be added. If antioxidants are added, there will be It may cause antioxidants to precipitate at the cathode and be included in the coating, affecting the appearance and reliability of the coating

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