Water-based cleaning-free flux for lead-free welding flux and preparation method thereof

Abstract

The invention discloses a water-based cleaning-free flux for a lead-free welding flux and a preparation method thereof. The flux is suitable to be coated on the welding surface of a printed circuit board by a spraying and dipping mode, and mainly comprises deionized water, a composite mixed activator, a surface active agent, a composite mixed cosolvent, a film-forming agent, a corrosion inhibitor, a microorganism growth inhibitor, and the like. According to the water-based cleaning-free flux for the lead-free welding flux, prepared by the invention, the content of a VOC (Volatile Organic Compound) is lower than 5%, so the environmental-friendliness is achieved; and as necessary, the microorganism growth inhibitor is added, so that the water-based cleaning-free flux has certain stability during the storage process. The water-based cleaning-free flux for the lead-free welding flux, prepared by the invention, has the comprehensive advantages that halogen is free, residuals are fewer, cleaning is free, dielectric resistance is high, combustion is difficult, the storage and the transportation are convenient, the environmental-protection effect is achieved, and the like; the combined circuit is simple and rapid, the raw materials are easy to obtain, and the price is lower; and the water-based cleaning-free flux for the lead-free welding flux is suitable for large scale preparation and industrial production.

Description

technical field [0001] The invention relates to a water-based no-clean flux for lead-free solder and a preparation method thereof, which is a kind of halogen-free, non-volatile organic matter-free and film-forming flux specially used for lead-free solder on the soldering surface of a printed circuit board (PCB). water-based no-clean flux. Background technique [0002] Solder is an important connection material for surface mount technology (SMT), and Sn-Pb solder has been widely used in all levels of soldering in electronic packaging in the past few decades. In recent years, studies have found that the use of heavy metal lead seriously pollutes the environment and damages human health. With the increasing awareness of human environmental protection, various countries have begun to introduce various laws and regulations to restrict the use of lead in electronic assembly products. Therefore, lead-free soldering technology has become a domestic and foreign research hotspot. ...

AI Technical Summary

Problems solved by technology

Rosin-based fluxes are widely used in the electronics industry, and can be used in high-reliability products after cleaning with chlorofluorocarbons (CFCs), but such fluxes are restricted for environmental reasons

In the early 1980s, the water-soluble fluxes developed by people were usually only used for the soldering of non-electronic products, and they had to be cleaned strictly. With the development of fine-pitch devices, cleaning of micro-components was difficult due to small gaps and other reasons. Therefore, water-soluble fluxes cannot be widely used

[0004] However, the current water-based no-clean flux for lead-free solder has certain disadvantages: the surface tension of water makes the flux wettability poor; The activity of the flux is weak; the melting point of the lead-free solder is high, which will easily cause the volatilization of the flux activator; there are more residues after soldering, strong corrosion and deliquescence, resulting in reduced insulation performance, etc.

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